I have the Creative Bundle and I have some issues. I'll continue studying, but I thought it's good to throw the question here as well.
 
- Multiband Harmonizer can not be opened in a project which includes Perfect Space and Vocal Strip without immediate "Fatal error" crash.
Using safe mode loading I tried to spot which one of the mentioned is actually guilty, because sometimes
the other didn't cause crash, sometimes the other.
I did not find a confirmation yet to whether the harmonizer should be configured as a synth or a time based FX, but it does seem to work better as a synth. How should it be?
 
- The whole bundle is installed in the same location, at the same time, but some of them give a "the software is not properly installed"- error and get only the mute substitute in the FX-bin.
 
I've liked very much all the ones I've been able to use, so I'm interested in learning, if there are any known quirks for SONAR 8.5.
 
Any experiences? Thank you in advance.

I hesitate to even mention it because it's such a rare occurrence, but it sounds as though the harmonizer plugin and Perfect Space might share a common CLSID. Though rare, it does happen (I've not seen it happen with VSTs, but have with other plugins in other applications). When it does, there is nothing you can do about it except to avoid using that combination of plugins. 

Hi Kalle
This might be a little out of date, but a few years ago I did try a number of the Melda plug ins - I did like them but I seem to remember they were not 100% stable - I did not buy them and install them at that time - as I said that was a few years ago - Sorry I can't be of more help.
Nigel

Fyi the developer is very active on Melda's forum on KVR.  I'd post a message over there if you wanted a direct answer. 

I wrote a poem about it...

http://forum.cakewalk.com/tm.aspx?m=2662266

There seems to be fresh updates available for all Melda VSTs. I must try those.