MultiMC is another modded minecraft launcher that makes it fairly easy to build your own packs. I have had nothing but problems with it trying to build even simple small packs in MC 1.7.10 (it worked just fine with 1.6.4).
My solution is to set the launcher for the version # I downloaded instead of recommended, then make all the changes I want, then update the individual mods myself. The only problem comes when forge needs to be updated. This last DW20 update I was able to download the new version to get the forge update, replace the mods, config & saved game folders with the old, altered ones, then update the few mods that needed the newer version of forge.