I am in the EXACT same position. We plan to do a Friday morning at MK (party day), then leave at lunch and head over to AK around 5:30pm. Our FOP FP is for 6:55. I, too, would love to have some FPs for use at MK that morning, but honestly, FOP is a priority for us, and I have a semi-antsy 9 year old and two elderly-ish parents coming along, so 2 hour waits are literally not an option for us. I figure we can get enough done that morning in MK if we arrive early and have reasonable expectations. We've done everything in MK more times than we can count, so if we're in and out and only get 4 or so attractions in and only stand-by, we can live with that. Also, factor in what the crowds will be like during your trip and AK day. Our week will be fairly crowded this year, and our AK day is a Friday, so I'm not taking any chances that the end of day FOP line will be short and sweet. Not sure when you're going. Maybe if it were a Monday night on a slow week, I'd be tempted to release it.
Editing to add: I see by your ticker we will be there the same week. We go the week after thanksgiving every year and I do not think this year will be slow in any way whatsoever. I'd keep your FP.