I use the MB4210 combo using Fender Jazz basses. As already said, the combo is more than powerful enough to rehearse in a rock band although I also trot out the extension cab for gigs (for much the same reasons!). Very versatile as well covering a wide range of sounds.
Its fair to say that when some of the first MB amps came out, some had some QC issues, but Marshall got them sorted quite quickly and their customer service is second to none.