I blended Crisp MO with Wyermann Barke Pilsner and Rahr Premium pilsner, I think the ratio was something close to even among all malts for a German pilsner. The beer turned out very nice and I got 2 silver medals with it, but I thought the Maris Otter came through as somewhat sweet, bready like and the beer lack the grainy cracker I have gotten with straight up Wyermann Pilsner malt.
I blend malt all the time and it changes depending on the beer I'm making. If I were to do that Pilsner again, I would back the Maris Otter off a bit, or maybe drop it altogether. That same beer with a Bohemian Pilsner malt won like 3 golds for me and I thought it was a better beer. Then again if I'm brewing for myself and I want that breadiness in a beer, I would leave it around 30%.
I don't think the 10% MO would get lost in some beers (lighter beers) but in heaver, darker beers I think it would not be very noticeable. Can you buy them in bulk and keep them separate? That way you can experiment with blends with different beers.