As with many polls I come across, none of the options available seemed to specifically suit how I felt I wanted to respond. I chose one anyway, since this isn't anything other than casual conversation online and won't affect anything at all.
I fall in a group of folks similar to many guys I know who would rather have the option of choosing a S&W revolver without the ILS. It's 3 metal parts and 2 springs for which I have no personal need (4 metal parts if you count the key required to operate the ILS).
However, I own several S&W revolvers, one of which is equipped with the ILS, a M&P 340 Centennial. I would've bought it without the ILS if it had been an option.
Two of the other more recent S&W revolvers I bought were a 37-2 & 642-1. Both were produced after the introduction of the ILS in the S&W revolver line, and were limited in availability. I bought them because I like Airweights, especially the 642-1, and they were available without the ILS. The newer 642-1 complements an 'original' 642-1 I picked up and which became my favorite off-duty J-frame ... and then my favorite off-duty weapon overall. I thought I might as well have a spare, considering how much I enjoy shooting it, and because the similar pre-ILS model suddenly became available.
That said, my M&P 340 hasn't offered me any trouble regarding the ILS. I've fired several hundred rounds through it so far, and have allowed a number of other instructors to try it on many occasions, with more than a hundred-plus of those rounds being full power Magnum loads. No unintentional ILS engagement. Accurate little wheelgun. It had a couple of other minor QC type issues which I resolved myself (as an armorer), but none related to the ILS.
I've handled and fired some other ILS-equipped J-frames, too, and have observed a number of LE and non-LE users shoot them, and I haven't experienced or observed any ILS-involved problems to date. I know a number of other LE folks carrying various J-frames equipped with the ILS, some of whom are also instructors and shooters. Nobody has yet to experience an ILS-related problem.
NMSP issues the 637, I believe. I just heard of another major city agency which is apparently going to issue an Airweight or Airlite to their folks. I've asked a couple of different folks at S&W if any LE contract orders for J-frames are being produced without the ILS, and I've been told each time that the guns they've heard being shipped are normal production models which have the normal features, including the ILS. I wouldn't expect these folks to have personal knowledge of each and every order that has been placed, or may be placed, however. Who knows?
I recently talked to another S&W revolver armorer who expressed his enjoyment in shooting several hundred rounds of full power Magnums through a 340PD. Enjoyment, huh?
Anyway, the point is that he didn't report any ILS-related issues with his gun, and he said he was planning to pick up an M&P 340.
There are folks who have posted their experiences regarding problems they believe are related to the presence of the ILS and its unintentional engagement during shooting. They can be found among the internet forums.
There are some other issues that can occur in a revolver which can 'lock up' the action, and as a LE armorer I've learned to withhold my opinion about what may have happened (or didn't happen) in some situation until I've either had the opportunity to examine and inspect a firearm reportedly experiencing a problem myself, or listened to someone else whom I trust and respect who had the opportunity to personally examine the gun. Too many things can happen which can be mistaken for something else, and people sometimes seem prone to jump to conclusions. I've long since lost track of the times one of our folks brought me a gun with some definitive statement about the nature of "the problem", only to discover that it was something else entirely. Or else there wasn't any problem with the gun at all, but something had occurred involving the shooter, the ammunition being used, the shooter's maintenance practices (or lack thereof) or the conditions under which the gun had been used at the time the gun had experienced 'the problem'.
Going back, I'd prefer the option of choosing a S&W revolver without the ILS feature. That's me. I practice safe firearms handling, manipulation, use, prevent access to my weapons by unauthorized persons and I practice safe storage.
Other folks have expressed their opinion that they actually like the option of being able to use and engage the ILS.
Lots of other folks apparently don't have any negative opinions at all about buying a S&W revolver equipped with the feature.
I've considered buying a new M40 at some point. Maybe. It's not like I
need one. I have more than enough J-frames to meet my needs for off-duty weapons and later retirement CCW weapons. If do choose to buy one it'll be because I'd like to have another steel-framed .38 Spl (only) model ... maybe the nickel model to replace a nickeled M36 I really liked but follishly traded away long ago ... and the M40 doesn't have the ILS.
Of course, I'm sure there are folks who will eventually surface and claim the grip safety feature can malfunction or cause the gun to fail to fire if the grip isn't 'good enough' to depress it.
FWIW, I think on another forum's website there's an ongoing long thread about the S&W ILS topic in which there's a couple of reported instances of Taurus revolvers supposedly unintentionally engaging and locking up the guns during shooting. Dunno. I wasn't there and didn't have the chance to examine the alleged guns myself.
(There are so many of these threads on this subject that they start to blur together after a while.)
Another thought which occurs to me is that as our society continues to evolve and the number of people increase, I wouldn't be at all surprised to eventually see that such internal locking systems are going to be the wave of the future when it comes to safety legislation. You don't really think that the major firearm manufacturers haven't already considered this potential and may be anticipating it, do you?