I can play with delay using clean or crunch sounds without any problems. Only in high gain sound Is get a lot of feedback in between playing which makes the delay useless.
In short: High gain without delay: No noise while playing and in breaks.
with delay: noisy feedback while playing and a lot of feedback when not playing or breaks in slow lead parts.
I did not have much time to test your advices but I did one thing which seems to improve the sound a lot. My amp loop and the TF were both running in guitar level mode. I changed the TF to line level and it seems to be much better. I still need to try the different combinations on loop/TF to find out the best for me.