Seeing as we're talking about the sound reproduction of THUNDERBIRDS we should be able to do this here. My 'problem' with 210s isn't necessarily bass extension (which is dependent on physical design factors, not diameter), it's more that they probably aren't going to move a lot of air. Given a choice I would always go for 4 x 12s or 2 x 15s -- although the 212 is thunderous enough for my needs.
There are plenty of compact and lightweight 212s*. Then again if you are going to have PA support and only need a stage monitor 210 is prolly fine -- TWO would be better.
* Smaller and lighter than the 29kg SVT212AV, which I wanted because it's 4Ω.