I will definitely sell some into the gapup; I always do. Gotta take those guaranteed profits. A lot of gaps fill, and then if it dips below yesterday's close, the gap sell is the only profits for the day as I sell at that point and will rarely by back in that morning. I only stick with obvious strength - best way to preserve capital and stay consistently profitable (although the profits are low sometimes until you hit a sweet ticker).
Your strategy isn't bad, but my preference is not to sell during the run up (other than the gap sell) - I sell all at a sign of large weakness (typically 6-8% dip, assuming it is a big run). Sometimes, if the run up is really strong, I continually buy the run all the way up, and then sell as soon as the execution price starts to fall. I literally just keep buying at market every minute if the bid keeps going up, and then just sell all as soon as the bid drops twice in a row. I made a ton doing this on FNMA - it only works on the strongest runs, but when it hits, it can be great. As long as you sell immediately on a sign of weakness and the ticker is liquid, you generally won't loose trading like this provided the run from the gap is at least 8%.
PMCM may have an epic run - but it may gap too high and fall from there; you never really know (which is why I always take some gap up profits, which also locks in profits from the prior trading day).
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