Thought i'd check back in for a quick update. All the gear sold really quickly no problem. Only Line 6 thing I still use is an M13 though I do plan to treat myself to a JTV-89F one day.
After all the messing around trying to get the DT25/HD500 to produce the sounds I wanted, I gave up. I thought the DT25 was a great little amp but the killer feature for me was being able to use the HD500 with it to effectively get more channels than i'd ever need for perfect tone on demand.
Trouble is, I could never quite get the sounds I heard on the standalone amp to reproduce when using it with the 500, the vast volume differences (yes I understand why they happen) between different sounds was a pain and sometimes the 500 would just do random stuff and need a reboot. Not good mid gig.
I ended up replacing it all with a (used) Mesa Boogie Roadking. Yes it cost an arm and a leg but bloody hell it does everything I want.
4 channels with 3 different voicings and you can switch between 6L6 and EL34 valves on the fly as required. Boost button for solos and you can equalise the volumes across all the channels to taste. Glass like cleans, to chime to crunch to high gain madness, it does it all.
Had it about 6 months now and no regrets or complaints other than the cost and the weight of the damn thing.
If you get the chance, try one.