[raymo]

You have a bit of a problem. The 6SE would be a good choice for visual, having a reasonable aperture, and being portable, although it's great focal length would prevent you from framing the entirety of some of the larger nebulae. The negative aspect of this scope is that it is photographically
quite slow, meaning that it requires long exposures [minutes] to obtain decent pics of most deep sky objects other than the moon, sun, or planets,
and it's alt/azimuth mount is not really suitable for long exposures due to a
phenomenon called field rotation.
Dobs are popular for visual, and the collapsible ones with GOTO are easily
portable, but the base is quite bulky, especially in models over 6". Dobs are
also alt/azimuth mounts, so are also not suitable for long exposures. They
are however much faster at around f4.7 to f6, so can produce worthwhile images using far shorter exposures than the 6SE , especially in the case of the larger ones [8" or larger ].
raymo