From the postings I 've read, the Blue Diamond and Blue Pearl seem to be the most reliable robotic cleaners. I cannot decide on which one to get. The Blue Pearl takes much longer cleaning time than the Blue Diamond, 4 hrs vs. 1 hr. Does that mean the Blue Diamond is going to last 4 times longer? Therefore the warranty on the Blue Diamond is 4 years while on the Blue Pearl is only 1 year. Is it worth the $300 difference? Anyone has bad experience with these machines?