The problem with the Ultra 2 is you can only load 3.8 software (3.74 actually runs better, but . . .) That's ten year old software.
Of course you can load DocuSP 2.1 but that's twenty year old software with known issues.
It makes for a very slow controller that IS better than the DT135, but only marginally so.
If you are really serious about moving up in the world, consider a Blade w/ an LCD monitor. You don't need a floppy, but you will need a DVD drive as all the newer software is on DVD. If you are considering the future, get an X86 box as Xerox stopped Sparc updates with 51_SP2 Prices for hardware are so low that using an Ultra 2 is penny-wise.
There's also slim, a one piece EDN cable that makes for a neater installation and eliminates the pesky pigtail. It resembles the cable that connected the old tape drive on the DT135.
Still, the EDN180 and Core 180 (which you will need for the conversion) is worth $2K of the asking price.