The project is looking good Cliff!! Nice and clean and professional. A thought about your Bessey's, I just got done Googling and looking for any complaints about the Bessy's not being strong enough I was hard pressed to find any. My first instinct when I saw your clamping was that first off, those clamps are better fitted to panel and case glue ups, the handles are not made for max torque, because you cannot get max torque from spindle handles, the grip is just not there, those C Clamps you are using are waaaay better suited to provide the clamping power you would need for small bulky glue ups like you are doing in that image. The proper clamps need to be used for certain glue ups, just like we need the proper tools for certain aspects of woodworking, clamping is no different. Once those joints swelled from the glue, those K-Body's were not the right choice to grab and try to bring that joint to close. The C clamps were definitely the proper clamp for that job.
Those Pony pipe clamps are really good too at closing troublesome joints, you can get a ton of torque with the lever style handles, unlike the smaller spindle handles of the Bessey's. Again, you used the proper clamp for the job. I see you really torqued down those Ponies by the looks of the pipe flexing, this is where the Ponies excell, I have a good stash of the Pipe Clamps myself and love them for large glue ups and for troubled joints.
I have no doubt if you put a pipe clamp up on the handles of the Bessey's you would be able to close the trouble mortise and tenons in your earlier images. That is the biggest difference between the clamps you used, the handles, you can apply waaaaay more torque with lever handles such as you have on the C Clamps and the Pipe Clamps. Again, the proper clamp for the job is very important here.
The Bessey's excel at large frame and panel glue-ups, that is the original intention for their use.