hi mystikal
I have a 200mm dob and its great on planets. you even get plenty colour in the planets which you may or may not get will 100mm. you can also do what i did, mount the ota of the dob on an eq mount later... the cg5 could handle the 8" for visual work and pictures of planets pretty easy (not so great for astrophotography of DSOs). it all comes down to how much you want to spend i guess