[apfubar]

What I can say is the following:
- dx10t - is now an older radio from Spektrum, which has and continues to receive updates(apparently there is one in the works at the moment - Andy on RcGroups stated this). It is however discontinued, and replaced by the 18t, so you should get a good deal on it.
I would however recommend you carefully consider the limitations of the 10t, particularly the number of mixes... This may force you down to the 18t, in the spektrum line(I think the 18t has a similar number of mixes to the 18).
It does support 18 channels, which is good, and the buttons on the sticks(assuming it is the standard sticks) are frankly brilliant.

- Graupner- I have only used the mc32, not the 20.... They are pretty similar... given the mc20 only has 10 channels, check and confirm that this is enough for what you need. Also confirm that you have enough sliders for control surfaces, as there aren't as many mixes.
It is a bit harder in my view to program than the spektrum, but it is more flexible. The Hott system can do some really cool stuff in the receiver...
Oh yeah, if you are familiar with Spektrums model match, be aware Graupner does not offer this at all(any models bound and switched on will receive commands regardless of what model is selected).

i hope that helps a little, as stated above feel free to ask any specific q's.

Cheers,
AP.
P.s. I do currently use Dx9, dx18 and Graupner MC32 radios