Of course you could just keep the 22 AND buy a 17 to use as your competition gun
In reality, the 22 has the minor disadvantage that you'll be shooting snappier .40SW while all the other kids will be shooting those re-coil-less 9mm in Production. If you can handle the snap and get quick split double taps, then do it. Other disadvantage is ammo cost. 40 is just more expensive to either buy or re-load, so if you plan to shoot a lot, say over a 1000 rounds per month, it's going to add up to some $$s whether you re-load or buy factory.
If you were thinking of shooting Standard, then the 22 has some goodness, it's an easy way to get into Major, and score some additional points if you can. You can also do a couple more things to the gun in Standard (that you can't in Production).
I had a G22 a couple of years ago and sold it to buy a G17 for competition. I've since moved to a Tanfoglio for competition as I really like the single action trigger over the stock glock.
It's a decision you should try to make before you start competitions as you'll end up buying a bunch of mags, and possibly different holster if you decide to switch.