People do it all the time. Just have to clean all the carpet and glue off the floor of the boat. Thats a pain to do but possible. I think it's easier to put carpet back down. I have done it twice in my bass boat and it's not to bad once you get the pattern down. Also with bed liner it gets very hot to walk on in the summer time.
how long does your carpet last on a average?
The first time i did it i used indoor/outdoor carpet from Home Depot and it lasted about 4 years of heavy use on front deck. The back deck still looked good. When i replaced it the second time i used good boat carpet (High fiber count) it has now lasted 5 years and still going strong.