We are going to replace a conventional bathtub with a whirlpool air tub or waterjet tub.  Anyone have experience with either of these? Which brands do you prefer and why?  Which is best for a bad back- spinal stenosis?  Is the sloped back, which seems to be very popular today, or the straight back tub better?  It is so hard to pick out a tub as you can't use it before buying and spending a lot of money to install it.  We may go to a hotel and try one out before buying.  I read the article in CR but couldn't find any ratings on them.  Are there any yet?