Thanks for the advice everyone. I just got back from the Hotsprings dealer and made the choice to go OEM. The obvious clincher was realizing that my lifter is actually Hotsprings compatible after all - I think it’s an “upright lifter” - so when I saw the OEM would a drop-in, coupled with a pretty good price < $500 (delivery extra), plus quality I can feel, it was an easy choice. The dealer stated (but I haven’t confirmed) the foam is at least 2#, the slope is 4”x3”, and the warranty is 2yrs. He said it should last for 5yrs.
Other tidbits: he cautioned against a floater stating that it would linger at the intake port, distributing chemical above one spot, potentially chemically burning the seat.
In my searching over the last couple of days I think I found a few alternatives to Core Covers in the US. Just for comparison sake, here’s my list:
Ideal (ca)/ spacoversusa (might be the same)
Prestige / beyond nice (probably the same)
Nashville
Commercial fabrics
Cal spas
Arctic spas
Acculok
Thanks again for the suggestions, in four weeks, I’ll be hot tub happy again!