I don't know how it compares to other joints, but internal sleeved joints that are plug/rosette welded and butt welded are commonly used in all kinds of racing, so I wouldn't worry about the sleeve joint. I've been doing alot of research on cages as I'm about to start my first cage (research including cages from race cars, because there's alot of good information there as well!)
Alot of stuff that I've seen specifies that the sleeve extend at least 2x the tube diameter inside each tube (so if 2" tube, then the sleeve needs to be at least 8" long, 4" on each side?), the sleeve wall thickness the same as the main tube wall thickness, a fit that's not loose, and then 4 rosette welds. Not sure if that means 4 on each side, or 4 total. It seems to be a very common joint, even on a brand new cage, not just a repair job.
How often do yall use sleeve joints on newly constructed cages?