Yeah Sean, layout does matter as soon as you care about a bandwidth beyond a few hundred kHz. That is one of the things that set Spectral's design off from some others. In fact there is/was a PS Audio preamp that more or less borrowed the same circuit (really, really close) but did not sound worth a damn, imho. Although it may have been one of the better PS Audio units. The layout just was not up to the same standards...side by side the PS looked like a clusterknot compared to the Spectral.
Take a look at the Halcro amp, they had to pay attention to RF layout as well... (not for raw bandwidth, but to keep wide bandwidth so that the feedback would work to drop the distortion 2 orders of magnitude lower than usual).
_-_-bear