I have ran individual campaigns that combined the realm of mentalism and essence into one realm (essence), while keeping channeling. I have also ran a campaign combining all realms into one (essence). Both worked ok, and I prefer one realm over the divisions, but it took a lot of work.
I would like to see spell users in the future follow the channeling companion templates, were all base list are grouped together and the spell user picks his base list based on things such as culture, education, guild affiliation, GM fiat, whatever. My favorite aspect of this approach is it removes the cookie cutter result current base list provide (all mages/mentalist/etc are alike with the same spells).
I am thinking of making onle one realm available in my next campaign; channeling. I will merge all the base list with the Channeling Companion base list and all spell users will choose their base six. I am looking at a bg option cost for access to certain base list, or the ability to pick other base list beyond the six while no bg expenditure will result in random other base list generation.
I have created PC's before using random base list generation to generate a feeling of "this are the magic list that were available durring your apprenticeship" feeling. It worked well enough, though some players did not care for it. I am, however, fortunate to have very experienced and mature players with open minds.
I like the list system, but I am open to some major overhauling of the realms.
lynn