If you really want to do astrophoto, then you must use a driven mount, period. Goto is fine, but it's not a requirement, all you need is a tracking mount (a mount that spins around one axis, doing 360 deg in 24 hours, and spins steadily, that's all) - this is something many beginners are confused about.
Many people will tell you to not start with AP directly, but instead spend some time doing visual observations and kind of "get your bearings", so to speak. You don't need a scope to take awesome photos, all you need is a camera and a tracking mount, which you could even build yourself out of plywood and scrap components:
That's because the critical requirements are a dark sky and, of course, the tracking mount. The light gathering ability of a larger aperture is secondary in importance, at least in the beginning.
The little NexStar is actually pretty "meh" for AP. You could get the dobson instead, spend some time learning the sky, and experiment with AP using a camera and a simple mount. You could even use the dob to take photos of bright objects such as the Moon or some large planets. Once you get all that stuff down pat, you'll make a much better choice of AP equipment.
Real AP gear is expensive and finicky - GEM mounts, Ritchey-Chretien scopes, apo refractors, etc.
The 6 SE is not much more than a toy, for AP. The XT8, on the other hand, is a decent visual scope. In their respective fields, they are not equivalent.
Finally, real AP is not entirely about the gear; a lot of it is about the knowledge that operates it.