I'm not surprised that GTI > R for sales. R already comes with an IS38, logical upgrade would be a hybrid if you really want more power for money. Also i'm sure many more people own a GTI vs the $16,000 more expensive GTI with AWD
Also, speaking as an R owner, the hybrid IS38 turbo, whether it be a vortex or whatever, has been tried and proven over the last few years. So naturally, someone with a R will know what to expect when they get one. The DTR is still a brand new contender with very little first hand customer data. So naturally people with IS38's such as myself, are a little skeptical if it really is an improvement or not, and by how much. That's why I really want to get some track and dyno data out of my setup to try and answer those questions for the other R owners out there.
On the other hand, if you have a GTI with a IS20, the DTR will hands down be an improvement, and for 1500$, it costs about the same as an IS38, plus the tune is included, and you don't even need a downpipe for it... naturally just makes sense to go with the DTR.