Assuming 1) Brainstorm isn't in the list and 2) Getting your Bosium Strip stopped by fetchlands is a real problem, then one could consider building a fetch-less multicolour manabase by just running 4 duals, then up to 4 Ravnica duals, then up to 4 painlands, etc.

The downsides are a slightly increased life loss (although I would guess no more than 1 point/game) and less ability to dodge Wasteland, so you should ponder the implications.