I'd say its power depends a LOT on the DM's willingness to go along with you and your levels/available books.
1. The more metamagic reducers are allowed for Heighten, the better the SCM is. If Easy/Practical Heighten are allowed by the DM, the build shoots up in power.
2. If you're playing at level 12+, then SCM is a lot more effective than 1-20, since as you noted the reality % on level 1-6 spells won't be very good until lategame.
3. Versatility is only as good as your imagination and book count. If you only have core and races of stone, SCM isn't particularly good - but if you can dumpster-dive for any evocation or conj: summoning/creation spell ever, it is much stronger. Sort of like a druid.
4. Finally, there's no consensus on what 110% reality constitutes. A DM is perfectly justified in ruling that a 110% real fireball does 10d6 just like a 100% real one. So depending on DM, there's no real benefit past 100% reality, except that the more you add on, the closer you get to the 100% mark with lower level spells.
With that said, the flavor is awesome, and its only 5 levels, enough to fit in incantatrix, recaster, red wizard, shadowcaster, master specialist, or whatever else you want to be incredibly powerful.