Just flew YUL-ZRH in 5K, in the Stübli.

Here are my thoughts:

As 5K is an odd-numbered seat, it is closer to the window, with the console on the aisle.
I found that the seat is VERY close to the window, so my should was essentially pressed up against the wall of the aircraft, not in an uncomfortable manner, but slightly annoying.
Anecdotally, I'm a "squisher" fellow (not obese, but I have a dad bod) so that might have been a contributing factor.

The added privacy of having just two rows and being separated from F and the main J by a curtain at both ends was lovely, service was quick and attentive, and the cabin was incredibly quiet and calm.

In the past, I've only ever flown in the Throne seats (just been lucky that I always was assigned those or able to select them). I actually found that the leg / foot space was LARGER and more comfortable in the single seat than on the throne seats.

My one complaint about the LX A330 J cabin is the hard product is really tired, it's long overdue for an update. My seat worked fine, but the guy across the aisle couldn't get his seat to recline. The cabin crew had to manually fold it down to bed mode, and then back up before landing.
I also think that a more substantial pillow would make a world of difference when it comes to sleeping, the pillow is comically thin and flimsy. Fine for lounge mode for a little extra lumbar support, but basically useless for sleeping.

Overall, LX A330 J is what I remember it to be: excellent service, quality catering, good wines, and liquors but a hard product that lags behind.

Maybe I am just spoiled being based in Montréal, 99% of my flying is on Air Canada with their signature class pods & proper bedding.