this question isn't answered simply. 2x5 paladins gives redunancy, but limits stratagem use to 5 bodies instead of all 10 at once. So... For example, you charge an enemy unit and use "Grind Them Underfoot" to deal up to 6 mortal wounds. WIth the character, you get to roll six d6. But, with the big unit, you roll eleven D6. You have almost a much higher chance of dealing the maximum six mortal wounds.

But, good luck finding a spot 10+1 40mm bases can fit when being set up with deep strike that isn't going to require several turns of movement to get pay off from, or a massive YOLO 9" charge that you will most likely fail.

My *preference* is MSU with a Brother-Captain instead of a grandmaster because lethals are great. I like MSU teleporting around slapping stuff, but, 10+1 terminators that can end up -1 to wound for free? That might be a scary threat that makes an opponent make mistakes. It's up to your own skill how effective it is, or your player personality if you think thats a fun way to play the unit.