Hi Fox, I calculate you are imaging at about f/12.3 right now, based on the size of the planet (44.6 arcsec), the maximum width of Jupiter in your image in pixels (90 pixels), the diameter of your OTA (127mm) and the equation shown below (from
here).
I also use a 2.5x PM, and it is pretty unique when it comes to barlows in that it
decreases its magnification the further away from the back of the barlow, while most barlows increase their magnification (including the 5x). The 5x PM might be giving you much greater than 5x magnification.
http://www.televue.com/engine/TV3b_p...id=53&Tab=_app
From what I know about other cameras (which isn't much), the key requirement for a "planetary" camera is low read noise and fast capture speeds. The 294MC has a low read noise value (the 224 is lower, but not by too much) and fast transfer rates in 8-bit mode (but not as fast as the 224), so should be good for planetary with the added bonus of being excellent for DSO and the moon. DSO cameras are not my thing, so I can't really help you there.
That being said, if I want to capture the full moon in one shot, I use my DSLR or capture lots of images with the 224MC and use a Photostitching program like Microsoft's Image Composite Editor which does an excellent job (yes, really!).
I would highly recommend getting a finder, I use the Bintel (rebranded GSO) 8x50 RACI.
Andrew