Welcome to our forum.
I know nothing about *these* models, but I'll comment on my previous spa, the PDC, which also had a lot of the hardware under the steps. I don't know about this one, but the arrangement there was that the steps were sort of a loose cover where the spa pack sat under the steps. Mine was set into a deck, so was above the ground. However, if it had been on the ground, I know I would have had a lot of bugs and other things making their way inside.That's why I like the more totally sealed arrangement of SD and others like it. Are these models you looked at sealed where the plumbing from the pumps enter the 'inside'? Or is the step a closed extension of the cabinet to keep outside things outside?
The step sits ontop of the spapack and screw into the side of the tub, it is as sealed as any other tub out there. No tub is sealed tight. The spapack has a floor to it as well so the pump and heater are not sitting on the ground, under the step is also where you drain it. I meant to comment about the step in my last post regarding it's height, they do sell a smaller add on step but we felt it was not necessary. We have 3 kids, 12, 10 and 7 and no problems getting in and out. Ray