As mentioned previously, I think it's worth investing some time into getting to the bottom of the initial pin-hole problem. With a good technique, you should be able to get parts with near perfect surface cosmetics. If you're envelope bagging, then have a close look at the mould surface, but this should be quite noticeable if there are lumps and bumps transferring to your finished parts

Bear in mind that the GC50 is best applied using the G100 gel-coat cup gun. It might be prone to fish-eyeing if brush applied and getting an even application that won't slightly distort the cosmetic look of your parts might be tricky. The GC50 is great stuff and gives a nice polish-able surface coating, with the flexibility to use spray-tacks more reliably, but investing in a small compressor and the cup gun is probably the way to go if cosmetics are highly important

When using the XCR coating resin, it's viscosity can lead to lots of air being trapped in it during mixing, so allowing it time to de-gas prior to application can reduce the chance of bubbles popping on the surface and curing to leave craters. Also, it's a good idea to quickly cover parts after coating, to limit the chance that dust particles will settle on it and leave nibs that will result in small craters once sanded. 

Addressing the cause of the defects in your parts will likely be of most benefit to you and it's likely something simple that you  need to change or repair