Put it on, get that break in started. Although, I disagree with ratell. The B17 is probably what most people that ride in a more upright position use. It's what it seems to be made for. What would make it uncomfortable is if you're going to have a more aggressive saddle to bar drop on your new bike.

Obviously saddles fit people differently though so it might be great for you on both bikes. I personally can't stand the b17. It's painful for me, my thighs rub the 'wings'.. it's just my anatomy I guess, but the Swallow and Swift that I have are nice saddles.