As far as using a delay pedal in the loop of my HR50+, I have a MXR Carbon Copy that I don't like in the Soldano loop. I use it with other amps. It sounds ok on low gain settings of the normal channel but with gain on the overdrive channel it doesn't sound good at all.
For the HR, I also use the TC Gmajor 2..........it is awesome. Just as already said by lynch, the effects on it are sweet and the channel switching capability is something I really like.