I used a couple of fuel processors on my V-rod, which runs even leaner from the factory than my VN900 does(!) and they are all about the same. If the PC3 for the VN900 is the same as the ones I've seen - they're pretty good.
Don't expect that it will turn your bike into a tire eating monster. It won't.
It will allow you to tweak your F/A mixture back into the "sweet" spot after a pipe/intake mod.
I like the V&H Fuel Pack (check fleabay) since you do not have to run wires down to the injectors, and you don't need a computer to access the device. The interface is a little harder to deal with - but FOR ME, and FOR A V-ROD, the install was cleaner - and once you get it tweaked in for your riding preferences, you're going to tuck it away on your bike somewhere and forget about it until you tinker with your bike's engine again.
My preferences are HD biased - since the install on my other bike is in a Waaaay different place than it would be for the VN900, but it's something to think about.
IMHO - they all work about the same in the end
If you want to monkey with your F/A settings a lot - and you don't mind running wires down to your injectors - the PC3 is hard to beat, and there are probably a ton of maps out there for different exhaust/intake configurations.
The Cobra (Fi200r?) uses the "tweak-the-pot" method for adjusting the F/A mix - which is all you need - and it's simple to use - but you have those wires to deal with (hide.)
Let us know how it turns out!!!!