Re: Are all Hum Cancelling Singles just as quiet?
I'd expect some variation. They use different shielding techniques, some may cancel noise less perfectly to attempt to preserve more of the original tone, some don't even bother with shielding instead relying on the stack to deal with all the noise...
There's also differences in tolerance.
I don't know who is least noisy or generally best in the current generation. DiMarzio's current models have some divergence in tone from a vintage single coil (and not because they're noise cancelling). Kinman tends towards brasher sounding A5 designs. Opinions vary wildly on Bill Lawrence's AirGap models.
The Lace models I've tried just struck me as weird, though I haven't tried the Hot Gold that fans claimed was much closer to a classic single coil tone. [I've tried a red dually, silver middle and blue neck in a Strat Ultra. I think I'd have liked blue bridge, gold middle & silver neck better... but there are a ton of new variants now.]
I'd probably choose based on tone. If you like Seymour Duncan's single coils, they're the only manufacturers doing a precise duplicate of a particular known single coil as a noiseless pickup that I know of.