DGS has a SPIO vest but he has cerebral palsy and it's for giving him input from his body, specifically the trunk. When he's wearing it it sits much better and his riding was noticeably straighter, so I know its effective for him.
It's pretty expensive to import, I think about an extra £30 on the purchase price. Make sure you get any import tax refunded (need to contact border agency for that).
The SPIO vest is a double lycra fabric (like a leotard) so can be warm in the summer, it's pretty ok in the winter but DGS is not good at controlling his body temperature so he overheats easily. I think this would be an issue with any body suit though.
The vest stretches massively though and has so far lasted around 18 months and still got loads of wear in it. It's easy to put on too. The vest is pretty much for physical disability as it's a double lycra, the other garments, long sleeved top and leggings are singles and are possibly better as sensory garments.
I'm not sure about the sensory hug but it would probably worth trying the cheaper garment before going for the SPIO vest. If the sensory hug is too hot maybe go for the SPIO?