The 294 offers the larger sensor size and image…..but also has the larger pixels so not a great sampling match for your Redcat scope. It is also kinda finicky for some folks with getting proper flat frames….it’s a pretty specific process apparently that demands some discipline or there will be significant artifacts in the image
The 183 sensor is much smaller as are its pixels…..it’s a much better match sampling wise but you really can’t take full advantage of the widefield of the Redcat UNLESS you practiced Mosaics….in that case, you’ve likely put together the best possible scope/sensor option available
The 533 sensor is a tiny bit larger overall than the 183 and the pixel size is a bit larger too…..an ok sampling match for the Redcat but even better for 500-800mm focal lengths. This sensor generation is of the most recent so image quality wise…..you’ll get cleaner images with more dynamic range in less time than either of the previous two. That’s NOT to say the 183 and 294 can’t……..it will just take more time and work
And then there’s the pay once/cry once option of the ASI2600…….the same chip specs as the 533 just much larger so you can get the full view available from your Redcat without mosaics.
So here’s the scope inherent demand…..it’s a Petzval so the full image is flat…..a perfect mating for the 2600 APS C sensor while the smaller sensors of the 183 and 533 won’t see nearly 50% of that field and IMO are best suited for optical systems with existing field curvature or inherent structural issues that result in tilt……..these little sensors ‘see’ only the center of the image on a scale that all but eliminates tilt, curvature and vignette.
My $$ say the cooler months are upon us so hold on to your $$ and your DSLR…..the noise will be less of a problem now till mid spring. In the mean time, find a way to stash away a few more $$ each week that gets you to the 2600……you’ll want for nothing for a few years and longer focal lengths after.