How did this go. Not that I have done this much but I have checked and ReDrum (and other) sequences copy exactly as played, velocity etc so they should sound the same so long as there isn't some other factor introducing something that wasn't there before.
Have you checked to see if Groove settings have been altered or doubled-up in the change of sequencers?
Otherwise I'd think it was psychological as it does seem more exciting to have patters trigger on a ReDrum than from a boring old MIDI track LOL Maybe try rendering both Loops and then popping them into a player or wave editor to see if they seem the same. Even play at the same time with Phases swapped to see if they cancel.