Just to add my real world experience ... I currently have a terrible chain line on my twenty 10mm+ out (short chain-stays) and a borrowed 44 tooth multi speed ring on the front

No issues in the slightest .... I've not dropped the chain or heard any unusual noise. I've not pushed it really hard yet though.

I wouldn't worry about your 2mm ... but if you really want you can fit spacer's ... I've got spacer's on mine to improve the chain line while I get the BB sorted.