I used to have some of those on my old MTB – IMO the best rim brakes ever. I also seem to remember that you shouldn't have to disconnect the hoses, but if I'm wrong and you do, then yes, you'd have to bleed them. And be careful about what fluid because If I remember correctly Maguras use mineral oil (I have Martas on my MTB). I think Magura call it Royal Blood or something comedic like that, but you need to make sure you use the correct fluid. Not sure how easy they are to bleed, as my HS33s never gave me any trouble, but the Martas were a bugger to bleed. My LBS tried twice (and charged me twice) and still couldn't do it. I took it to a proper shop (MountainTRAX in Wokingham) and they did it right first time for half the price and they've been great since.