I haven't yet, but some clients come to me with a contract in hand instead of doing a recording - I surmise these are the ones that are likely to object and I don't usually even ask.

Typically, I'll still sign their boilerplate, but I ask that things like NDA, work-for-hire, and non-compete are either eliminated or toned down such as to still clearly permit unmitigated action in the open source space.

The last time I did a "recorded contract" was over a year ago, which makes me now feel sheepish about saying "these days." :-)

I don't think it will be the last though, and I do highly recommend it.