Update on stability:
I tested the new version and it does appear to be a bit more stable than previous releases but not rock solid yet.
On my 6-core it got stuck on a block when I found that block (luckily I did get the block reward after I restarted the client).
On my 4-core and 2-core machines it was hanging on a grant-block.
I haven't seen it crash yet (runtime error) except when I started mining while still loading the blockchain.

I will do some more testing to see if I can find something usefull to help debug. Then I will switch back to XPM until a new Memorycoin client comes with more stability fixes.