If you're not racing or race training there's no need for a standard double. Use a set up that suits the pace you intend to ride at. You said "longer distance riding ... maybe some light touring ... it won't be raced fit mudguards and panniers ... an all rounder", none of which suggests a race double to be the best choice. But then again, if you're using 6800 the BCD doesn't change so you can swap between compact and double rings any time you like.
If you're not racing or race training there's no need for a standard double. Use a set up that suits the pace you intend to ride at. You said "longer distance riding ... maybe some light touring ... it won't be raced fit mudguards and panniers ... an all rounder", none of which suggests a race double to be the best choice. But then again, if you're using 6800 the BCD doesn't change so you can swap between compact and double rings any time you like.
/sick of internet hardmen rant