I have the full size Dainese Manis D1 that I use with the Laguna Seca suit and with everything the correct size it is all perfectly comfortable. Mainly use it on track but have been out for a few road rides and it is still fine for less aggressive riding positions.
Like everything it always comes down to getting the right size and fit, last thing you want is anything to distract you gear wise when riding.
Good thing about the Manis protector is it comes in different lengths and chest/waist sizes so at 6'3 I can get total back coverage without having to have some XXXL one.
Both my jackets have all the inserts in though, far more convenient for everyday use!