Except that with full battens lasy jacks foul
unless you get them out of the way before
hoisting. That is a headache IMHO.

How many boat had full roach mains? Not
all that many.

"Marc" wrote
The Duthman is a partial answer at best. They are impractical for full
batten full roached mains as they need a topping lift to operate.
Sailors with full roached mains want to get RID of topping lifts,
hence the advent of solid vangs. Kind of stupid to sail with a topping
lift only for the purpose of flaking your main. A well designed
lazyjack system is the answer for all applications.