Resistance to change isn't really the issue, Sarah ... I'm sure I'm not alone in finding the new nav sidebar simply unusable.

The visual clash between it and the main area is really difficult on the eye, and as for the sidebar itself, white text on a black background is a long-time readability no-no. Having to distinguish between black and the dark grey of submenus is equally difficult.

I've had similar feedback from clients, so the alternatives you've provided are very welcome.