What about parallel loops. I had an Alchemist for a week and it didn't seem intrusive at all.
That is because Parrallel loops also feed the standard clean signal through as well.
This can be a nightmare when using fx processors and certain effects as they dont work quite right.
When i had my marshall TSL a friend brought his g major over and you couldnt hear the delays on clean sounds at all as the pass through signal was more dominant than the effect.
Loops can be great though when done right.
To be honest i have a small hatred to fx loops for the tonal change between the same amp with & without the loop its just too much for me to be a fan of them.
It could also have something to do with the fact that i arent the biggest effects user as i like amp tones rather than modified ones.
If i do use them i generally apply them afterwards in a DAW to keep the tone as its meant to be