The facts indicate that a TC30 is CONSIDERABLY more tractor than a 790. You've left out a number of particulars that drive pricing, like tires, transmission, etc.
For me, it would be an absoute no brainer.
I drove a TC30 quite a bit before I decided on the
B7800 Kubota. I really liked that tractor except for the excessive engine vibrations (motor mounts were flimsy) ... For the money, the TC30 specs are hard to beat.
TIRES: R4s will NOT resist punctures better than R1s but they will load up and lose traction faster. R4s are meant to be a compromise providing a certain traction advantage over turf tires but less ground wear & tear than an R1 (ag).