The KiwiSix is one of two boards I’ve heard of that adds more patch memory. It has 1024, with full MIDI CC and SYSEX support. Johannes Hausensteiner has a MIDI kit that also expands memory to 128. The other various MIDI kits only affect the key assigner board (KLM-366) not the programmer board (KLM-367). The two clone KLM-367 out there (one from Jed and Andy, one from Old Crow) are really clones with no change in functionality. Tubbutec has two kits for Polysix. The ModyPoly adds MIDI, some new unison modes, arpeggiator functions and a Sample and Hold feature for the filter. The PolySex does some interesting pitch modulation with a couple of extra LFOs. The Kenton MIDI kit does note on/off and program change via both MIDI IN and MIDI OUT, as well as patch dump and load (SYSEX) but still with 32 patches. MIDI IN also handles pitch wheel, mod wheel. CHD ELEKTROSERVIS has a MIDI kit that also looks like it handles eight other CC#.
Did I miss any current kits? Sorry if I gave your favorite kit a less-than-complete description.