The upgrade kit includes ALPS pots for volume and balance.
As far as who has done the upgrade, they only released 15 kits based on this comment by Doc on the
Bottlehead forum: "We were only able to get 15 of the rather unique Alps Blue MN taper balance pots with a center detent, hence ony (sic) 15 kits in this initial run. More pots are on backorder and the ETA is around the end of January."
I plan on adding the kit later this winter. In the meantime I'm enjoying my stock Moreplay (tubes upgraded to Tung Sol) with my ST-35.