As far as velocity vs weight: I don't subscribe to caliber wars. Get what you can control. The rest is about shot placement.
However, I do want to state that I would probably pass on the Hydra-Shoks unless you're getting a really good deal on them (free). Otherwise, they're old technology (1985!) and there are better rounds out there.
I prefer the Federal Tactical HST 124gr +P JHP. Or the Speer Gold Dot 124gr. I want to try the 147gr +P HST next and the Gold Dots in +P varieties. I'm very good with the Gold Dots, but the +P HSTs are quite snappy and I'm still getting used to them.

If you want to do a little research on why you might want to pass on the Hydra-Shok, here is some great reading material.

http://9x19mm.com/forum/viewtopic.php?t=456
(Pay particular attention to posts by "Snowman366" - he gives some really convincing first-hand accounts.)

http://frag.110mb.com/

http://findarticles.com/p/articles/mi_m0BTT/is_168_28/ai_112685770/pg_1?tag=artBody;col1

http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm
(Halfway down the page there is a summary of Federal HS vs HST. Be sure to also follow the links to the Wound ballistics workshop articles which were good reads too).

Great quote from this article:


Whatever you choose, by 3 boxes - keep one to carry and shoot the other 2! Repeat at least once a month, pending finances.

In my line of work, when you supply your own carry ammo, unlike LEOs, you find yourself considering price as well as expansion. On that basis, I have found that although an older round, Federal 9BPLE balances expansion and cost pretty well. I cannot conceive that much of a difference if my carry round makes a pretty flower pattern in gelatin or not. With proper shot placement..... Now I'm not saying that any of these rounds aren't great, hard hitting stoppers. I just don't think it makes that much difference for the price.