I was a Cakewalk user. Haven't played with anything like that in ages and hadn't (not that I'd really looked much) found anything close enough for me in Linux. After an initial play with Rosegarden, I think even if get used to it, I would prefer Cakewalk but I should be able to manage my old type of midi dabblings with it.

As for learning curves, I think I would find the learning curve for Ardour far to steep for anything I want (and Audacity does me) but I thought it might be worth a mention.