I think the 34 is a competition oriented version. 9mm, a bit longer than a 17, adjustable sights and lighter trigger I believe.
Welcome to the forum Gunsmithie23, pop over to the introduction section and tell us a bit about ya. Great group here, you will enjoy it.
See I was thinking about either the 17 or the 34 mainly cheap rounds plus if I get a full sized gun like that I probebly won't carry it although I am able to carry and hide my full size M&P 45 quite Easily. So I don't know I suppose I should probably go and rent each so I can shoot them and decide. And I went on the introduction page and told everyone a little bit about me.
You have to figure out what class you want to shoot, If you just want to shoot production, get the 34, if you are thinking about shooting about limited, get the 35. This is for IPSC/USPSA, I know nothing of IDPA other than I don't like a lot of their rules so I don't shoot it. if you are shooting 3 gun, get the 34. Why I stated this is because, 40 offers no advantage in production, you want a power factor of 125 or so (weigh x velocity/1000) which scores minor, all production is scored as minor. If you shoot limited you can't shoot major with a 9mm, no mater what your PF, so load for to major PF(165) is the way to go and take advantage of the major scoring. 3 gun doesn't use PF unless your shooting IDPA 3 gun from what I hear.
I have the 35 that I shoot in limited USPSA. But yea I would look into what class you want to shoot in. If you want to sup up your gun at all then I would go for a 35 limited. If you just want to shoot your stock gun then I would go with the 34 for production.