That weight difference would barely be noticeable, and I would also keep in mind what rod you’re putting the reel on. If the rod is relatively heavy its nice to have a little extra weight on the reel to balance it. On the contrary, if the rod is really light (a helios for example) its nice to get a really light reel to best balance the rod. Unless you’re fishing the lightest of rods, I wouldn’t use a 10% weight difference as the sole reason to choose one reel over the other.
I’m not sure what you’re looking to use this 6 weight for, but keep in mind that it’s very infrequent that you need 100+ yards of backing. Honestly, I can’t think of any freshwater situation that you would need that much backing. Definitely not for trout, bass, etc. Carp can run you well into your backing, but 100 yards is a hell of a long way. If you’re using it for salt, that’s a different story.
Good luck. I’m sure you’ll be happy with whichever one you choose.
Tim