I also have heard very good things about D-1. I looked at them last year when picking out my tub. I wasn't thrilled with the salesman (a "pro" from the manufactuer who was on site for a one day sale...too high pressure for me), but I liked the tub. The only thing I wasn't too keen on was they used a UV ozinator (as opposed to a CD, corona discharge unit). I
think they now use CD, but you might want to double check.