I think it's already been said but the main issue with higher MP isn't the spec so much as the EHP or ability to survive. With enough EHP virtually any build will work, though it's likely they'll be outperformed by the SNS build (CMWW with shocking aspect and diamond shards). It's the same at lower MP in that virtually any build will work, provided you can survive, it just happens that Archon is highly efficient compared to most.
Crusader DPS and EHP Spreadsheet, meant for Crusaders
My Wizard