I may be out-of-touch on this one but my knowledge tells me that Harris-Tarkett's Longstrip collection 'floats'; not the Engineereed series. From here, you may need to enlighten me on my confusion. Are you being told that the Engineered floor floats? Basically, it's true, that with a floating floor you needn't put down any type of subfloor or underlayment. (I'll stop right there.) I'll tell you that in order for a warranty to be enforced, you need to be sure you have the proper subfloor / underlayment in place. If you have a bad particle board sub-floor, I'd check with Harris-Tarkett to see if they'll warranty the installation (whether or not you do it yourself or if you have a contractor do it.) If they say they will, be sure to take some pictures of the subfloor BEFORE you have the new floor installed. A video goes a longgggg way when it comes time to file for a warranty.
As far as refinishing an Engineered floor from Harris-Tarkett, the answer is YES. They can be refinished 2, maybe 3 times. You can, basically, refinish this type of floor to just about the tongue part of the strip. Depending on how much wood is removed from the surface will determine whether or not you'll ever get 3 refinishings out of the floor. Hope this helps. Best to ya.