When pixel peeping, technically there could be a (small) benefit from shooting through a somewhat magenta filter, to compensate for the denser Red/Blue filters in the Bayer CFA. That would require less boosting of those channels which would help to reduce noise a bit.
Hi Bart, your idea is fine (in fact some people use it), when there is enough light to have a good exposure at base ISO. For instance it will produce cleaner shadows in well lit high contrast scenes. But if there is a lack of light (need to push ISO), it would have an overall negative impact on noise. In this situation the more photons you collect the better.
Aside from that, having channels with different sensitivity (i.e. G ending with higher levels in the RAW file) can have some advantage for B&W photography: while G can get clipped in the highlights, you can still 'recover' a nice grayscale gradient from the R and/or B channels there. The G channel will help you in having sufficiently noiseless shadows. Kind of inter-channel HDR that enhances DR for B&W, specially if some strategy is applied to weight more higher SNR channels on each image area.
That is one of the reasons why paradoxically I don't think monochrome sensors are the best option for B&W photography. When the Leica Monochrome has its highlights clipped, there is nothing to do there: pure white, zero information. This is much harder to happen on a Bayer sensor, where you need to severily overexpose to blow the three channels at the same time. Instead monochrome sensors are dramatically digital, right the opposite concept Leica represents. If I had that camera I would tend to underexpose a bit in order not to ruin the highlights, but this would reduce potential DR.
Another disadvantage of monochrome sensors is that you cannot apply software colour filters, which are very flexible and straightforward.
Back to the topic, in general exposing for B&W is less demanding than doing for colour. If you are lucky to have a mirrorless camera you can even previsualize in B&W.