I have a site that's been upgraded to 1.5.20, but is still in Legacy mode.

I have a clone made with Working Copy. I am trying to eliminate Legacy Mode, in anticipation of 1.6, and because I have another important component, very recent, which is having issues, and I want to elminate Legacy before I bother the developers.

There are no Modules, Components, or Plugins in the Extension Manager listed as Incompatible.

Other than experimentation, turning off one thing at a time, is there any rational way to proceed? Does there happen to be a compatibility checker extension or service?

Thanks,
K