I have a Kubota L3430 HSTC with the factory cab. It is absolutely great; exceptional vision, quiet, very cool today/AC (93 and humid today in Minnesota), comfortable, and easy to get in and out of. The heater and cab are ideal for snow removal (primary reason I purchased the tractor).
I looked at putting an aftermarket cab on my old tractor (NH/Ford 3930), but decided against it. The aftermarket cabs were ill-fitting, noisy, hard to get in and out of, and of no use in the summertime unless AC was somehow jerry rigged into it.
My recommendation would be to wait until the DX 33 is offered with a factory cab or trade the DX 33 for a CUT with a factory cab. Before you buy an aftermarket cab for your tractor, go out and drive one with a factory cab with all the amenities especially AC. I believe, like me, you'd be hard pressed to invest several thousand dollars in an aftermarket cab for your current CUT.
Mowing and snowblowing in comfort!
OrangeGuy