I have a small farm of 36GPUs (gigabyte windfire & saphire 280x's), been running "ethos" for past year but month by month it has become more and more unstable with cards dropping out, so 1 or 2 per rig won't mine, and speeds dropped for 280x's from 19mh now down to 13-14mh. Would the hash be higher running claymore in windows on get off ethos?
You're better off mining something else other than Ethereum. I'm surprised you're still mining ETH with 280x's to be honest.
EXP is another dagger/hashimoto coin that works well with 280x. I'm sure some others here may have some recommendations for you as well.