marks just have different gain voicing than rectos. no matter how hard you try you can't get it to sound brittle. it's so fucking smooth and has more mids than the earths core.
the thing with the mark amps is they don't really kick into optimal tone range unless you really drive the power tubes a lot. they have more gain believ it or not in the front end of the amp and you can get a good lead tone at lower volumes but to really get it growling and screaming you gotta have some physical space to crank it.
the lead tone is hands down the best, on a iic+ and iv. IMO it is unrivaled in any amp ever. the rest of it is very good also. its just extremely clean and defined unlike more high gain modern amps where you need all types of stuff to get that.