I can understand the irritation of having one product fail and ruining another product but I just checked the Opus Solutions website and the warranty info. (which every purchaser presumably read) has this statement:
"OPUS Solutions, Inc. does not accept liability beyond the remedies set forth in this warranty statement or liability for incidental or consequential damages, including without limitation any liability for products not being available for use or for lost data or software." I'll bet you'll find something like this in the warranty for any other computer power supply or product you buy.
I'm not a lawyer but wouldn't the "incidental or consequential damages" exclusion mean they aren't legally bound to replace a fried motherboard since the "remedies set forth" are limited to repair or replacement of a defective Opus Solutions product. There are some state-to-state variations in warranty laws that may mean that Opus can't enforce this limitation everywhere but I don't know about what states do what.
If Opus replaces anyone's motherboard, it may be more of a goodwill gesture than a legal necessity.
Just my 2 cents worth because it seems from what I have read hear that Opus Solutions is a very small company trying to develop products most other companies don't provide and they may not be able to absorb the cost of blown motherboards with less pain than anyone else. If it was a big corporation building yet another dc-dc converter meant to be powered by an external brick ac-dc supply, I'd be less sympathetic. I have no connection with Opus Solutions either. I will admit to heaving a selfish sigh of relief that for once I didn't get in a rush and buy one of the 90w supplies and an M10000 when I was thinking about it. I put it off because I've got too many unfinished projects in the pipe already.