I can't really justify selling my old one to get the Mk3 (I'm kinda more tempted to get a Hagen and keeping my current one). I do sometimes think if I love this amp as much as I do, then maybe the Mk3 is my ultimate amp though.
I would like 4 channels of delicious Diezel tone, so Hagen has 1 extra and may give me a bit more of a raw rock tone, but the Mk3 Herbie has midi switchable -/+ mode. Currently my Ch2 gets used for pretty low gain crunch in '-' mode (just past 12 o'clock on gain), but there's a lot more fun to be had with that channel when I'm just playing about at home and can mess about with the + mode, so I'd love that to be switchable). My Ch3 is used for straight up massive heavy riffs by itself, but I've got a Chase Bliss Brothers pedal which is MIDI controllable, so I have additional boosts/drives on hand to expand the number of lighter crunch/blues flavours I get out channel 2, so it's kinda like a many-channel multi-flavour amp already from that respect.