Mineral wool?
Wow.
Well, I could care less about the insulation as long as it's easy to remove and reinstall for service.
I get these questions all the time on the phone, about 9 calls just in the last 24 hours asking what's the best spa to buy, (rather busy on a saturday night for this question).
My concerns are not what spa is good or bad - in this question you're asking about "H20" brand. Honestly, you may as well be asking about brand X.
What you're asking is too difficult a measure to apply to any particular brand of spa. You just can't supply an x or an o for a buy or don't buy block in the decision making process.
My personal preference is that the equipment underneath is as close to generic as possible, so that three to five years from now, when the spa is out of warranty (or in case the dealer's gone out of business - it happens all the time), that generic - aka - cheaper parts can be found to fix what's broke.
I recommend staying away from stereos, tv's, cd players... built in speakers that lift up from the corners, wild and crazy specially installed LED light strings - all of that stuff, (unless you're an electronics technician) is only asking for trouble later on. I service spas in the atlanta area and it's difficult enough for homeowners just to keep them running, much less have to deal with a major appliance that's a third to half the cost of a car when new.
I really don't want to spoil your fun, but put yourself in the position of being a spa owner looking for parts for it 3 to 5 years from now - or more.
The tub heck, it's a tub. Jets are jets. Insulation is insulation, But when it comes to broke heaters, controllers, and pumps - use wise judgement and think a few years down the road. The guts are what make it work. You and/or your warranty person will have to get it fixed.
