2.I know the reliablility with the G17 is awesome.Is the glock 23 in the same catergory?
3.If i get one it would most likely be a Gen 3.Are there any problems for those that have a Gen 4?
2. They're reliable unless you get a bad extractor or a bad magazine. Some of the newest extractors can be oversized and fit too tight, causing failures to feed. All you have to do is replace the extractor if that's the case. Some of the newest magazines may also fail to feed, there are protrusions of plastic at the front of the feed lips which may be too large and rub against the top round as it rises, slowing its rise and causing a failure to feed. All you have to do is shave those protrusions down until the magazine feeds reliably. I've had to do it to two magazines now.
Here's a picture showing the plastic protrusions, you don't have to follow the specific instructions in the picture, just shave those protrusions down until the magazines feeds reliably.
http://i51.tinypic.com/2a649he.jpg
3. The newest Glocks, both Gen3 and Gen4, both 9mm and .40 may have a problem with erratic ejection. This problem can usually be fixed by doing one or all of three things. Get the most recent guide rod version for Gen4, replace the extractor, or get the newest ejector. The newest ejector is being used in both Gen3 and Gen4 now.
Here's a picture of the newest ejectors, the picture says they're for Gen4 but they're being used in Gen3 now as well.
If the gun has this ejection problem, you'll notice some spent casings ejecting over your head, straight up, barely coming out of the ejection port, hitting you in the head or face, some going over the left side of the gun, some even ejecting over your left shoulder and downrange to the left. You'll also notice triangular dents/scrapes at the case mouth of most of the spent casings and brass dust collecting on the edges of the ejection port. You may even see some failures to eject.
1.
http://i44.tinypic.com/2irgpf.jpg
2.
http://media.photobucket.com/image/glock dent casing/mazdaoffroad/DSC02164.jpg
3.
http://media.photobucket.com/image/glock dent brass/hotrod9mm/40-S-W-Case.jpg