Blueranger,given the price of the myrtle wood cubes, it doesn't make sense not to try them. We're talking about $30 at the most.
I can't tell you how something is going to sound in your system and neither can anyone else! Let your ears be your guide. You should know as well as anyone else that something can sound excellent in one system and sound like crap in another. Its about system synergy(mixing and matching components)to obtain desired sonics.
Having said that, I've tried and am currently using the myrtle cuboids with very good results. However, I'm using mine in conjunction with maple wood platforms and mapleshade isoblocks.
Ideally, turntables should be seperated from other components, not in the same rack/stand. Wall mount being much better than most other applications. If you cannot afford to, then try experimenting with other possibilities, some of which I just mentioned, thats the only way you'll know for sure.