The water is mostly gone by late January / early Feb. I used to make a trip down there over X-mas but I've switched to Thanksgiving. The Salto will still be running b/c it's damn released, but everything else in SLP will be pretty low unless you get lucky with rain. T-Giving has been good th last couple of times- Santa Maria canyons, Micos, Verde, Ojo Frio and Salto are all going at that time. Grant runs a solid trip- I've run into his trips often and he seems to have things dialed for his clients. Unless you've clocked a lot of time down there and know the shuttle roads, you can wind up spending a lot time lost days off the river cause you can't find put-in, etc.
October- I'd love to hit it but it doesn't vibe with work, unfortunately. We did meet some folks who got down to Micos only to find about 5000 cfs cruising over the 20'-30' footers down there. Basically unrunnable. They had to drive south for a while and chill at the coast before coming back up when the water dropped. Some other friends of mine from Dgo went to SLP in Sept-Oct and everything was super high. They had a great time, but they were exceptional boaters but still pretty gripped on the Santa Maria. It sounds like you've got everything wired down there, though- have fun.
The stuff further south (Veracruz) is more consistent through the year, but you're still dependent on rains, and that whole coast is getting pretty dry by the middle of January.