Korgasm...

You have excellent setup.
I had 2 JV2080 too with many boards but i sold'em (except PCM boards) and i ordered XV88 and one XV5080 because they are 100% compatible.

Roland XV synths have ALL XP/JV (2080) waveforms so they're really 100% compatible with them. XV have also 112 waveforms from JD-990 (the best ones). These waveforms sound better on XV than XP/JV & JD because of then new fx routing and A/D (24 bit)converters. You can also use all JV PCM expansion and patches. (Up to 512 MBytes of sound ROM)

K2600 has KDFX installed plus better fx routing using updated algorithms. The sample option has new 20bit A/D with better s/n ratio. In K2600 Kurzweil redesigned the audio path and now the synth has new audio output circuit with new 8 balanced or unbalanced TRS outputs.
There is also a Digitech FX emulation mode that can be used with all programs and new filtering with 48 db filter resonance.
K2600 has also all new programs and setups, more memory and better (but still difficult) operating system.
Generally speaking 2600 is a refined K2500 with less bugs and more audio path power.