I have Sound Radix's 32 Lives that works very well with some older 32-bit AU instruments. It doesn't work with MX4. I asked Sound Radix if they plan on supporting it and they said:
"I'm afraid we don't have info regarding MX4. We've tried to acquire a copy from MOTU but wasn't successful as it was discontinued. Please forward any error or crash log, it'll greatly help us understand the problem and fix it."
Discontinued?
It is still listed at
http://www.motu.com/products/software/mx4 but I don't see it on the main software page at
https://www.motu.com/store/software/. Hmm.
Well if MOTU isn't going to update it maybe at least they can work with one of the companies doing the 32-bit wrappers.
*** UPDATE ***
I just downloaded the new 32 Lives 1.0.3 and MX4 sorta works! I didn't do much testing, but it loads old projects and seems to play them fine. The 1.0.3 release notes say the problem of plugin windows always floating on top of the main windows instead of going to the back when other windows are active has been fixed, but at least with MX4 that isn't the case for me. The MX4 window remains front-most, except the window borders with those red, yellow & green balls do go to the back, so then the only way to close the plugin window is to move the other DP windows around until the red ball is visible again. I have 3 monitors, so it isn't much trouble for me to just give a few instances of MX4 their own monitor, but it might be a problem for others.
I got 32 Lives cheap during the beta period and use it with a number of other AUs. It is pricier now. They do have a demo, so if you need MX4 in 64-bit mode you might want to give it a try. I have OS X 10.8.5 and DP 8.0.5. Maybe another setup works better.
http://www.soundradix.com/products/32-lives
