I don't really have a problem with UbiSoft undercutting their GOG prices with their Valve sale, because it's a sale. Sooner or later I'm sure GOG will have a sale on UbiSoft games (might I suggest 'buy two, get one free'?) which would then temporarily make the GOG versions cheaper. As it is the games were just released here, so they know for the first little while they can charge $9.99 and people will buy them. I have no problem with that (it's simple business sense) and to support UbiSoft's decision to bring their games to GOG I bought BG&E again (a while ago I bought the action-adventure pack that included PoP, Splinter Cell, and BG&E, so I already own the game).
From now on though it'll be a matter of UbiSoft swaying me into buying their games by convincing to open my wallet. I've already got twelve games on my account and I've only played five of them so I can wait for the GOG sales, but if I see a UbiSoft 'buy two, get one free' sale I can't see myself passing up that opportunity even with my current backlog of games (I also have two retail PC games and 4 Xbox360 games I need to get through).