If only the pad movement bothers you, you can always add lines or dots of 100% silicone to the underside of the pad. They help to keep it in place pretty well.
What type of pad are you currently using? I prefer ccf pads over inflatables in a hammock for a few reasons, but one is that the ccf is far grippier than the nylon shell of the inflatable and thus did far less skating around. I never tried an SPE, but wondered if encasing ccf in a nylon shell would cause the same issue. Ccf can be a bit clammy if laid on directly though.
As far as the Hennesys go, I'd think they would be relatively the same as the Eno in regards to pad stability. I had a BPUL but have never tried an Eno. Being on the smaller side (the hammock) for me at 5'11" I never had much trouble with a pad sliding around on me - wasn't much room for it to slide anywhere
The explorers are a bit larger for taller individuals if you fit that description, but of course a bit heavier as well. You certainly can't go wrong with REI's return policy if you decide it doesn't meet your needs.
You can always try an inexpensive solution like the silicone, or some have reported success with the rubbery shelf liner as well before spending your gift cards, and if it works, spend that money on something else