I wear both. I primarily wear the Launch for training, but do some runs in the Green Silence. All of my racing (5k on up) is in the T7 racer.
The Green Silence is a bit roomier, and fits true to size (I wear a 10 in both the GS and Launch). The T7 Racer is more snug and fits small (I wear a 10.5 in the T7). The heel to forefoot drop between the two is noticable, but only because the forefoot of the T7 is so low. The GS feels like there's a bit more in the forefoot, and I've found it's more comfortable for training runs. To me the GS just doesn't feel "fast." The T7 is much more flexible, and the snug fit makes it feel like more of a racing shoe.
The GS has no traction, so muddy trail runs are not recommended. That being said, they're great on well-maintained dry trails (think fire roads). The upper takes a bit of getting used to. The lacing pattern and intergrated tongue are weird, but there are several different lace holes so you can (eventually) get a custom fit. It seems like I'm knocking the shoes, but I think they're great. They're just a bit diffrent from most shoes on the market.
Bottom line: if you're racing in them (and doing speedwork), get the T7. If you're training in them (especially slower distance runs), get the GS.