So, I was debating the same thing you were not too long ago. 9mm or .40. I've read alot about both and was hell bent on getting a 9mm. I ended up buying a Shield .40. All I can tell you is that I love it. The recoil is not bad. I'm not going to use the word "manageable" because that would say that it has a lot of recoil. It is easy to control especially after shooting and seeing how it feels.
I'm glad that I bought the .40 but I also have a M&P 40C and had it way before the Shield. Honestly, if you can't find a Shield, stepping to the compact line is a great choice. Yes they are bigger all around but if you can't find a Shield, it's better to have a gun then not. I do not like Glocks either. The ergonomics are terrible. The M&Ps have always been my choice and will continue to be. I have had countless friends give up their ideas about owning Glocks and bought M&P Compacts.
Either way, good luck in trying to find one. I got mine through gunsamerica.com from a dealer in Maryland, I think. $450. I've seen them cheaper and more expensive but regardless the best firearm is the one that is in your hand. If you want a Shield get one, .40 is incredible and I'm sure the 9mm is terrific also. (I'm about to buy a 9mm barrel for my .40 Shield just for fun.) But I wouldn't wait to find one and in the mean time not have a solid weapon on my hip.
Good luck