I flew a bunch of StarTech "starters" last weekend, some with an old 6v Solar Controller, most with my 12v relay controller.
With the 6v Solar Controller, there was a noticeable lag between pressing the button and motor start, though all worked fine, and certainly better than the previous glue-tipped starters. With the 12v system, single motor rockets, they started much faster.
For my Hydra VII, I soldered all starter leads together, in parallel, to ensure any failure would not be due to poor connections, including some additional "shooter" wire to get all 7 together. All were held in with Estes pink plugs. Motors were 4xB6-0 and 3xC6-5. It was launched with my 12v relay system. At launch, there was noticeable lag when pressing the button, unlike 7x Q2G2s or old-style MJG BP motor starters. By sight and sound, it was clear that not all motors started at the same time. Still, 6 of 7 motors worked. Post-flight-analysis showed all igniters worked, so my working theory is that the rigid set of starters pulled out before all 7 motors started. With Q2G2s and old-style MJG, the Hydra VII always started instantly and leapt off the pad.
While more testing is warranted, it seems unlikely I'll be able to use these in place of lower-current starters for large clusters. I'm looking at Quickburst Hot Shot dip, just need to find a source of 26 or 28 awg "shooter" wire. The 24 awg seems a bit too thick for C6 nozzles.