Pros: Glove-like fit, warm, great performance
I have crazy feet. Very high arches, one foot a 10.5 and other a 9.5, Morton's toe, wide flair at the toes, and the obligatory '6th toe' bump at the 5th metatarsal. My boots have always required lots of work and blowing out of both shell's and stretching of the left shell (I buy shells to fit my small foot, then bump the heel pocket back slightly in the shell and bump out the toe box slightly for the larger foot). Despite this, I've never been able to get a boot to fit me comfortably for any length of time, and unbuckling my boots in the lift line was always standard operating procedure.
Getting the Intuition liners solved all my problems. I still need to get my shells worked on, but with the Intuitions inside they now fit like a perfectly fitted glove and are far warmer as well. On occasion I have needed to have them re-heated and re-fit due to a detached achilles and the large bump the surgery left on my left heel where they re-attached it, and re-fitting solved the problem (no charge by the shop). I have had my first liner re-heated three times and the plug liner redone twice.
When getting fit for the liners it is very important that they use a neoprene cap over your forefoot and toes, as this creates a bit more 'wiggle room' for the piggies, as well a bit of extra space for the common 5th metatarsal bump.
The plug liner is very thin and firm, but if heated long enough and then clamped as tight as you can into the boot during the cooling process, it will conform perfectly to your foot and be perfectly comfortable (although definitely not plush). I find I only need my buckles tightened very slightly to get my foot perfectly snugged into the boot, with no movement, and at this setting I can ski for a couple of hours without feeling the need to loosen the boot (unlike the couple of 'minutes' I could ski before I got the liners). In fact, they fit so well I can easily ski with only the top buckle done up for free skiing and not lose a great deal of performance.
There are other similar custom liners out there, but I have no experience with them so can't comment on the comparison. All I can say is that for someone with extremely challenging feet, I couldn't be happier.