Select betas may have been unstable (that's what betas are about) but 4.0? and Adjust appear to be *very* stable.
As for 'unproven' - try RO5 on anything but an Iyonix
I think I'm correct in saying that the Iyonix and RO5 precursors were developed together over a number of years as something other than desktop machines so advocating the use of RO5 for non-Iyonix products is more of a political requirement than a technological or useful exercise.
Like the ARMTwister, RO5 on non-Iyonix machines is yet to be shown to work. Unlike the ARMTwister there will be no (immediate) benefits if (and when) it can be shown to work.