I have both in the shop, but I don't use either for bedding, just repairs.
For bedding I use Marine-Tex. You will find that the major fiberglass stock makers use Marine-Tex more than any other brand. It is the most compatible of all brands with the material the stock is made of. Call the maker of your stock and ask what they use to bed their stocks.
Marine-Tex is found where ever they sell boats and boat products. It's like a gel when mixed.