Hi! The LS1082A module isn’t shipping yet, and does not work with Pocket Reform right now due to display incompatibility (this could change in the future, but there are no guarantees). LS1028A is interesting because the module is open hardware and has more powerful cores (but, yes only two) and up to 4x the RAM of the original Reform.
FWIW, iMX8M Plus is a fantastic module (especially running an overclock to 2.0 GHz), and eliminates the need for a separate wireless card. Future upgrades are in the works with other chips and I’d keep an eye out for those as they should offer bigger performance boosts.
The key difference is the Cortex-A72 cores, which are substantially faster than the Cortex-A52. The shop page says roughly double per core. It’s worth noting that even if the i.MX8MPlus has more, albeit slower cores, a substantial amount of tasks will be bound to the speed of a single core. How they will compare in practice is unclear.
Another neat thing about the LS1028A is that you get an extra PCI-E lane over the HDMI port. That’s pretty strange, but will enable some really cool tech, like external GPUs or other PCI-E cards.