Well, neither is going to really affect performance much. The BOV is slightly louder than the BPV, and both are sturdier than the stock BPV. So, if you want to get one, it basically comes down to whether or not you like the sound of the stock BPV or want something with a smidgen more volume.
These things are good complimentary mods if you have other things (such as a boost controller), but on their own on a stock car, you won't notice any difference.
As for Forge Motorsport as a shop, they are a great group of people. Very helpful. When we were doing the initial testing and install of the BOV on my car, we ran into a problem. They went out of their way to solve the problem, which wasn't even their fault at all (crappy mazda plastic piping is to blame).