I can't say for certain whether it's easy to get out of the window seats on the UD of a KE 747. But I believe that the new KE shell seats are very similar to SpaceBeds on SQ Megatops. Speaking strictly about getting out of the window seat on a Megatop, which may be sufficiently similar to a KE 744 to give you an idea, I'd say it requires a bit of careful stepping and holding onto handlebars (the agility-challenged might even consider it acrobatic), but it is definitely possible to get out of the window seat by stepping over your aisle-seat mate without waking him up.

If you think you can do it more or less nimbly enough, that leaves you with a straightforward question: do you (1) have confidence in your own ability to step lightly over your seatmate such that you'll feel comfortable getting up whenever you want to, or (2) trust that your as-yet-unknown window seatmate will be nimble enough to step over you in the aisle whenever he wants to get up? For me, that's an easy question to answer.

You?