Basing a comment on a pervious model is not the way to go. Don't you think you should know for sure before making a comment like that the GT3 can not be a daily driver? Check out a 997 GT3, read about it, see if they will let you drive one (most likely not, as they are all spoken for the next 2 years). Your beloved EVO magazine loves the damn thing, didn't you read their car of the year issue? It lost out by half a point I think to the 599 which makes sense considering porsche won the 1998, 1999, 2000, 2003, 2004, and 2005 car of the year competitions.
Your thinking on dyno's is very wrong. They are an integral tool in the automotive community. A dyno reading is not set in stone but gives perspective. If they were innacurate why would they use them? Why would they make different dyno's for AWD cars? I think you will find regardless of dyno a GT3 will put down more hp than an R8, period. There must be something to it if the GT3 with less hp and less displacement is able to out muscle an R8 (in reality more hp, ratings can be deceiving as in this case). The motor is highly underrated, 385 wheel hp is over 100 wheel horsepower per liter, simply amazing, no production motor does this, not even the f430 or carrera GT. Perhaps it is even a bargain having a cheaper base than the r8.
The AWD version of the 911 is not the only competitor to the R8. There is no RWD version of the R8, so the only one we can choose is AWD by default. I don't think that only C4S buyers are going to look at the R8, carrera S buyers would as well. The nice thing about porsche is they have every base covered, RWD, AWD, lightweight, turbo, naturally aspirated, etc. I don't think the GT3 is really the main competitor but it clearly can be compared due to the pricing. The GT3 is clearly a more visceral experience.