Thanks Richard! Think maybe it's a side effect from this SIR800DP FET used in this fashion? I'm think'n the "gate" is pin #4 on the FET? Looks like pins #1-3 are all goin to ground, so could just put the resistor over the pins? The Convoy C8 is delivered, but if it bothers the owner, I could look at fixing his. For now, I got a couple more of these A17HYBRID-S boards built up the same way, so I can see if it can be reproduced and experiment with a fix. Is there a downside to higher resistance? Best to go low as possible?
btw, I "only" got bout 5.7A max out of this driver to an old XM-L2 U2 1A on SinkPAD with 22 AWG wires. Definitely expected more, like about 6A. I know it's close, but... I tried another XM-L2 U2 1A LED and got the same max amps. I was thinking the SIR800DP would do as good as an original BLF17DD v1.0 with the original hot vishay FET. I didn't do a head-to-head, apples to apples compare test though, so I'm not sure if my tests mean much at this point.