A lot of companies produce class d mono amps. The main advantage to them is efficiency. Ab amps are typically only 60% efficient while class d's can be much higher. This makes class d's good for high power sub amps were you want like 1000 watts but dont want to kill your alternator. If you are thinking about maybe in the future using it for mids or highs then you should probably get a 2 channel ab amp. Class d's are typically used only for subs. As for being dirty its been debated but on a sub im not sure most people would even notice.
The only full range class d i know of is from xtant:
http://www.cardomain.com/item/XTAXTANT11