For one, bolting it in is very strong and I've never seen a (properly installed) bolt-in notch fail.....ever. I don't see any reason why you NEED to weld it in except for saving time but by the time you prep the notch and frame for welding I dunno if any time is really saved:think:.
I would be more willing to weld in wrap around notches than a DJM plate notch hands down. If your gonna weld something in make sure it'll support the frame in all directions....a plate DJM notch (which is totally adequate for bolt-on apps wouldn't be ideal for welding).
I've not welded on a NBS hydroformed frame...I've heard it's a little tricky but it obviously is done often. It would be your choice what to do...either solution will be cool.
As far as both it would be totally overkill...no reason to do both.
Cameron