Thoughts on 53E in Club?

I'm taking a last minute trip, so my seat choice is a bit limited. If I want to be on the UD, it's aisle or middle.

I normally luck out with 53A or 53K. I strongly prefer the UD (for the larger bathrooms and the extra storage bins with the window seats, not to mention in my experience it's a bit quieter than the LD). I dislike the aisle seats, as they feel a bit too exposed for my comfort and I never sleep as well.

Currently, all UD window seats in club are reserved, although I have a seat alert set up, just in case one frees up.

I've never sat in one of the middle seats. I keep seeing vague reference on Seat Guru (and similar) that the UD "E" seats have some sort of extra storage, but I don't recall ever seeing any such thing. Are they walking about the extra bit of space next to the armrest, where you could stick your eyeglasses, or is there some sort of extra cubby that I've never noticed?