Finally checked back into this thread....I honestly thought it had died on me...apparently not.
Anyways, I think I'm going to take advantage of Wolverine's September "Free Shipping on in stock handguns" and get myself an M&P or Glock.
Now the decision is: M&P or Glock!?!?
I've shot both of these pistols, both are excellent choices. I lean towards the M&P, as I find it fits my hand a bit better. But you should hold both to check to see how they fit your hand.
As far as your original question goes!
When I got into pistol shooting years ago, everyone told me to get a good quality .22 to start with, for the same reasons mentioned; inexpensive to shoot, allows you to learn good grip, sight alignment, etc.
After learning the above I bought a Colt Gold Cup, then a S&W 629. Although I had learned grip and sight alignment, etc. the .22 did not give me the opportunity to include handling recoil. So I basically had to learn how to shoot the larger caliber guns.
Oh, the .22 hardly ever came out of the safe after going to center fire pistols!
I got out of powder burning pistol shooting for a number of years, but I kept up shooting pistols, quality air gun pistols at 10 yards! These still provide grip and sight alignment, and cost waaaaayyyy less to feed (even compared to a .22), plus you can shoot them almost anywhere.
When I got back into powder burning pistol shooting again about a year ago, the first gun I purchased was a 9 mm! I didn't even consider a .22 this time, as I still have a few air pistols to train with.
As mentioned above, I have to agree the 9 mm is a great caliber to start with.
Sure you can shoot 50 rounds of .22 for around $4.00, but 9 mm can be had for around $12 - 13.00 for 50, less if you reload or use reloads.
The 9 mm prepares you for the recoil of larger calibers better, it's a lot more fun to shoot and unless you plan to shoot hundreds/thousands of rounds each time you go to the range (I shoot 100 - 150 of 9 mm per outing), the few extra dollars saved is not a huge factor IMO.
That my 2 cents!!!!
And yes, the Gen 4 is Glock's latest offering.