Thats the right idea. On a typical ale, I'll ferment aroun 65ish for 5 days, then slowly ramp up to room temp (~70). When the bulk of fermentation is done, warming it a bit helps the yeast make that last little effort. I've never noticed off flavors using this method.
Also are you doing AG or extract? With extract, you are locked into the fermentability of the wort they give you. In AG, you can adjust mash temperatures according to how fermentable you need the wort to be.
Also, out of curiosity, how far off are your actual FG's from the expected?