Well it's about friggin time, Thomas!
As much as I hate to suggest this, I think you need to hop on over to AVS and search for user input on those two screens. A common issue you will find with screen gain, is that it rarely is what the manufacture claims (much like projector lumen output).
Considering the environment you will be using the screen, you would benefit from a grey or silver screen, verse a neutral white screen. My screen is a Stewart Firehawk G3 screen. It's gain is 1.3, but it's 'real' gain is closer to 1.1.... It's a great screen, but you did mention "budget", so this one is probably not on the shopping list, unless you could find a used one.... The viewing cone isn't as tight as some might have you believe either. It'd work just fine for you.
