I think January will be busy, but not at the levels of the major holidays. It really depends on when you visit. MLK weekend will be busy. Marathon Weekend will be busy. FotA will bring in lots of locals once that kicks off. We have visited in January / early February a number of times and find the crowds to be far more manageable than Christmas or Spring Break, but rest assured, it's not dead.
We are not using LLMP for EPCOT, but we plan to use it for AK and MK this upcoming weekend. We also bought LLPP for HS as well as LLSP for a couple of the attractions, but only because our trip is a quick 2.5-day visit so we wanted to experience everything on our list with less stress. We also have park hopper tickets, so we will have more LL options open up to us and can go where there is greater availability / less crowds.
Based on what I've seen (I haven't experienced this system personally yet) it seems like at this point the best way to maximize LLMP is to book your three rides earlier in the day. As soon as you tap into a LL you can book another one, as you can always hold 3 LL's at one time (excluding any LLSP selections you made). So if you tap into your first LL right after you rope drop a few attractions, you have a good chance at getting a decent 4th, 5th, 6th, etc LL. If you have Park Hopper tickets, as soon as you tap into your first LL at your original park, you are open to book a LL at any park. Lots of possibilities there.
If your trip is longer, you might be able to get away with using LL less and focus on tackling rides at rope drop and park close.
FP+ had its faults, but I do miss it the skip-the-line feature being complimentary at WDW. We spent a pretty penny to ensure we can just walk into the parks and do what we want to do with little waits this upcoming weekend. I know we will be glad that we pulled the trigger, but the sticker shock still hurt when we paid for our LL experiences this past Friday...
