I have as long as one is careful to choose a well implemented and managed sidechain and one stays on the ball.

I personally would put only the value on sidechains that I could afford to lose.  This value would grow with time as the sidechains solution and the various implementations of it mature.

I would always only risk any value on a sidechain which could not fail in a way where someone else would end up with my BTC.  A failure mode would have to result in a total loss else I am utterly un-interested in playing.

My calculations are indeed very close to how I play Bitcoin itself.