I use the Spektrum Novak GTB.
In basic terms (for Jimmy
) the Spread Spektrum GTB operates at a higher frequency than the GTB.
This higher frequency smooths out the performance of the brushless motors. The reason it is specified for Spread Spektrum is that it can interfere with conventional radio waves ie. 40mhz FM. however 2.4Ghz Spread Spektrum is not effected by the higher frequency pumped out by the Spread Spektrum GTB.
PS. When I have had to run the spread Spektrum GTB with 40mhz I do get occasional glitching when on power, which does seem worse when using my better packs of batteries.