The 9mm/357 convertables have all SO FAR been built on the large-frame, so that's one issue: you have a gun "bigger and clunkier" than what you need.
Not that much, but there is a "handiness advantage" to the mid-frames. Also, quality control on the mid-frames is better...then again, you should do a full "checkout" on any Ruger (new or used) to weed out any bad ones.
The 357 cylinder and barrel on a convertible are absolutely normal, so they'll shoot well as long as the gun is OK.
The 9mm option may or may not shoot well. You're shooting bullets sized .355 to .356 in a .357 barrel. It can work, or it can suck
. Trying various rounds helps.
Now for the good news.
What you really ought to do with the 9mm is send it to either Gary Reeder in Arizona or the Bain & Davis gunshop in California. Reeder will convert it to 356GNR, which is a 41Magnum shell necked down to 357. With that cylinder you get to send a .357-size slug out at "supermagnum" speeds in the large-frame, tough Rugers
.
B&D can convert it to the 357-44B&D, which is a 44Mag shell necked down to 357. Same basic concept.
Either way you'll need to reload for these funky calibers. You'll need the special reloading and "shell necking" dies for these - Reeder and B&D can supply theirs.
Since the 9mm cylinder you're starting with is already fitted to your gun, it'll still be fitted when it comes back - it'll just be set up for the wildcat new caliber of your choice. A 125gr JHP doing over 1,800fps will put a SERIOUS hurt on whatever it hits
. These conversions are both set up to shoot .357-diameter bullets so even if the standard 9mm cylinder doesn't shoot well, it will in these altered calibers so long as the alignment is right - something you should scope out via "the checkout" before even buying this baby.
And any time you want, you can swap the normal 357Mag cylinder back in to shoot that or 38spl.