Q. Domibar 400 how comfortable for pillion rider? If we go long drive is it a good for both rider - Dominar 400?

Dominar 400 is a good choice and as it is segmented for cruising yet the pillion and rider seats aren't that much softer. It will hard to ride the bike for a long stretch without any hault. You may go for air cushions which will surely save your pillions

It ok but if the pillion doesn't sit right, you have issues to handle in curves

Yes it is true that pillion seat is not comfortable for long drive. specially for those have ht of 5'10"