I'm very happy with my D800 (and before that a D300s and several other Nikons) for daytime photography, but I'm getting more involved in astrophotography and feeling the urge I may have to jump ship (!). Admittedly, much of this feeling comes from reading AP reviews and web sites that are overwhelmingly Canon-centric. Two things make me think Canon may excel over Nikon. Not counting software (Backyard EOS, etc.), a plethora of Canon-centric AP products (i.e. clip in filters, numerous adapter choices, etc.), the big issues are that I plan to modify my AP camera myself and while this is reported to be fairly easy with many Canon cameras, it's also reported to be much more difficult with Nikons, and second, I've read that while Canon shuts off certain electrical systems located near the senor so there is no electrical illumination in long (several minutes) exposures, Nikon does not do this and suffers from that problem.
Does anyone have any first hand experience with these issues that can some shed light?