RE: RC10GT rumors...
I think you will be safe to buy a RC10GT for a while yet.
Based upon the TC4 release, the new GT will first come out as a Team Kit and will not have many hop ups and will not be faster right away than the old GT. Several months later the RTR version will appear. After everal months of track testing the Factory Team Kit will appear completely sorted out and it will out perform the old version.