I held off on the REDDI for a long time because of the size and unaffected 1/4" out. But it sounds amazing. I'm sure the Khan does, too. In this price/category they all sound good.
When I was buying, the Khan wasn't in this form. If it were, I may have considered it. I don't use my amp (Genzler that sounds fantastic) that much. Maybe 5-6 times a year. It might be nice if I could warm it up by putting a tube DI in front of it. But at this time (and it could change) it's not worth redoing my stuff. I play 9 of 10 gigs DI/IEM and the REDDI is just a great sound in my - and my band mates - ears. I'm guessing the Khan or any of them really, would be as well. Nice to have options.
I'm waiting for Jeff to come out with an updated version of the old Genz Benz Streamliner or something. Then maybe I can have a tube head that can work as a preamp and DI for supported gigs and as a nice tube combo amp for those gigs. That would be the ideal for me I think.