I recently moved from the ASI071MC-Pro (APS-C sensor) to the ASI2400-MC Pro (Full Frame Sensor). I have a William Optics 98FLT and William Optics 132FLT as my imaging telescopes. I have had great success for several years with the ASI071MC-Pro on these telescopes using the William Optics AFR-IV Flattener / Reducer and the 68II Flattener, The ASI071MC-Pro is a great camera.
Moving to a full frame sensor camera like the ASI2400MC-Pro requires a study of your telescopes and accessories. The full frame sensor is 36mm x 24mm but has a diagonal of 43.27mm. The telescope must provide at least that size or greater of fully illuminated image circle to avoid vignetting the image frame. You need to go to a full 48mm or greater imaging train diameter as well.
I had to upgrade to the William Optics Flat7 and Flat 68III to get a true image circle of 44.4mm. These flatteners provide a fully illuminated frame on the 132FLT but I still see a very slight vignetting on the 98FLT. Too slight to worry about as I can process that out. These flatteners are mechanically solid and no chance of image train sag or tilt when slewing to different parts of the sky.
You need to use 48mm (2-inch) filters and get the filter as close as possible to the sensor in your optical train. That was the easy part. I mounted the ASI2400-MC Pro directly to the ZWO EFW without using threaded adapters. I have a dark filter, clear filter, IDAS D1 filter, and the Optolong L-eNhance filter loaded in the filter wheel. The Optolong L-eNhance filter is awesome with both of these cameras, I highly recommend. The ASI-071MC-Pro has an AR window so you need a UV/IR cut filter but the ASI2400MC-Pro has a UV/IR cut window so you need a high quality clear filter with AR coating (Astronomik).
Sensor tilt and curvature was the next challenge. When I first installed the ASI2400MC-Pro on the 98FLT with the Flat7 0.8x Flattener / Reducer I had horrible sensor tilt and field curvature. Stars were bloated on one side of the frame and tight on the other side. I found the included M54 to M48 adapter from ZWO induced more sensor tilt. I ended up using the included M54 to M48 21mm extender and using the adjustment screws on the tilt plate I have almost adjusted out the sensor tilt but the curvature is still in need of a few clear nights to get the spacing dialed in. I am using CCD Inspector to assist with adjusting out the sensor tilt and curvature. Plan to use 5-10 nights adjusting the sensor tilt and dialing in the flattener spacing. I am sure more experienced astro-imagers could do this faster but I am learning as I go. I am having fun and that is what this hobby is about.
I still love my ASI071MC-Pro camera but the ASI2400MC-Pro camera is truly amazing. This camera has virtually no dark current. With the gain set to 148 the sensor does a mode switch and dark current drops to 1.5e. I only cool the camera to 0C and it is very stable. I will eventually try the ASI2400MC-Pro on my AstroTech 12RCT and see what field flattener I will need on that telescope but for now I am really enjoying the wide fields of a full frame sensor. Imaging at f/5 (495mm focal length) I can get the entire Veil Nebula, both east and west sections in one frame. I have also captured the Lagoon Nebula and Trifid Nebula in one frame.
Moving to a full frame sensor camera can be an enjoyable experience but plan for the challenges ahead. Your telescope must be able to provide a 43.3mm image circle after your flattener / reducer and you need to match the camera pixel size to your focal length. Too small of a pixel with a medium focal length telescope (600mm to 950mm) will put your resolution on the sky well below your normal seeing conditions. You will need to use 48mm or greater diameter filters and imaging adapters.
But once you get it all dialed in... it is amazing !