I'm still investing new contributions in stock funds but all the money I had in at that point was move to a MM fund.

Other than a total collapse of the banking system (and the Big O taking it) do I have to worry about anything having to do with this money except deciding when to jump back in?

We changed custodians, from Fidelity to another bunch early this year. There was going to be a "dead" period of around 3 weeks and I didn't want to be invested, so I moved to a MM fund in the old account and they transferred my $ to the new MM account. I've been there ever since with the exception of a small bit of an international fund. All my subsequent contributions have been to cash.

I wish there was someway to profit from the decline, like the SDS, but we don't have that option. I'd say the main thing to worry about, even if you nail the exact bottom, is that the market won't head north from that point for a long time (check out the 50s).