I just replaced my ZWO 1600MM with a 294MM and my first target to test it out on was the Helix.
About 12 hours of Ha, 5 of OIII and 1 each of RGB (for star colours) taken in a dark sky site with an RC8 + Mach1 mount.
Astrobin version is
here.
The 294 has a lot of amp glow compared to the 1600, and some very weird looking flats. But all seemed to calibrate out ok. Dew and wind provided some "fun" challenges too
Edit: updated attached image to latest version after a number of updates.