won't really add anything, except when using the amp standalone. although they may have done some undocumented tweaks to the model defaults...

meaning it could change your tones a little...

they did change some things for the DT50's (regarding a boost tube that doesn't exist on the DT25)

personally i'd do it, just to be certain that any work they;'ve done with fixes etc would be done....

realistically i don't think it'd matter much if you didn't do it..

I rolled mine back to v1.0 after a couple of days. I use my DT25 with an HD500. My patches (lots of them) significantly changed with v2.0. There were bigger volume differences between topologies.  Most of my patches became quite a bit louder. It seemed to lessen the distortion on some of my more rockin'  patches. It effected the way my compressor settings interacted with delays, reverbs and modulations.

But,it was no problem to roll it back to v1.0 so why not try it. You won't know if it'll make you happy unless you try it and you'll be up to date.

I just didn't want to re-tweak all my setting that I'm very happy with. You have to love the DT-HD combo!