My advise to you, is GO with big roach, in terms of performance it is way better. The jamming with the toping lift is minimal as it satys to one side of the sail, and altough you said you didn't want to adjust it all the time, its well worth the shore.
I have mine with a very very large roach, and still use a topping lift, (I don't want a rigid vang for other reasons) . My TL is marked where the boom will be when sail is not on, and all you have to do is lock it before lowering the main. For the increased performance its well worth having to ease the TL and after pull it!
But if you can get a rigid vang you're "golden".