Sout,
I mentioned that your setup needs very good light because a DSLR uses a much larger sensor that needs more light than a P&S camera. This has been discussed in the thread:
http://www.birdforum.net/showthread.php?t=92213 in with we both participated. IMO it is one of the most important advantages of P&S cameras in digiscoping - of course, a small sensor has important disadvantages also but this is another story.
My comment about long range is that your DSLR/Scope setup has a 38X fixed magnification factor. This is indeed more than a 500mm lens and a 2.0X TC wich has 32X (with a Canon DSLR having a 1.6 factor) and costs quite a bit less. However, this does not allow you to cover the range between 38X and 60X (long range), the accepted maximum effective range of a good digiscoping setup. This can be done quite easily with a good P&S digiscoping setup.
The way I see it Sout, is that digiscoping is a matter of compromises and one has to make choices. You made the choice of having a F/12 38X setup which obviously pleases you and this fine. Others will make different choices.
I am still at the stage of making that choice and I find it difficult because there are so many options. The first decision is pretty well made: I need a good scope anyway for birding - so I will most likely purchase a Pentax PF80EDA with the 20-60X zoom.
After that I still have to decide wich exepiece I will get for digiscoping. I have narrowed the choice to: XW20, XW14 or Maxview-PX.
I will use a used Canon A95 I just purchased to experiment and learn for a while, changing it to a more recent P&S later.
The option to use a DSLR with the PF80EDA is still open of course.