Was it a MK2? The difference between the 49/61MK2 and the 49/61 Essential is massive.
It was indeed a keylab 61 mk2. As far as I've been told, the keybed in the Keylab Mk2 (the real one) is directly from the Matrix Brute, so it's supposed to be fantastic.
Granted, it was in a used gear room at a SamAsh nearly a year ago... I was testing it side-by-side with a Novation SL49 mk3.
I thought the keys on the keylab felt hollow, and very much synth-style and not remotely into the "semi weighted" category that they're advertised as.
I preferred the action of the Novation, but I thought that the price did not justify it because I still didn't love it, either.
The best feeling semi-weighted keybed that I've ever touched was an Alesis VI61, but that feeling unfortunately didn't translate to actually playing it. Its velocity curves are not good and the black keys are significantly more sensitive (and there's no way to fix it)... to the tune of using gram weights to produce a MIDI velocity of ~80 would result in a ~120-125 on the black keys, tested at multiple of its velocity curves. I can deal with a little inconsistency, but not that much.
That being said, I've never gotten the chance to touch a Nord, or anything with a TP/40L. Based on what I've read, I think I would really enjoy a TP/40L.
What I'm after is essentially a hammer-action that is extremely light (and thus probably not graded). I just like the way that hammer actions feel... like I can make a small finger movement and the energy that my finger has pressed down is translated into (real world) velocity in something that has real weight (and therefore inertia).
I really dislike feeling the springs constantly pressing up on my fingers with synth-style actions.
My big restrictions are size, because of how my desk is laid out. My speakers are in the rear corners on qacoustics stands, so I have more depth in the middle, which is awkward. If it's an 88 key, it can't be deeper than ~13" (and I'd prefer it more slim than that).
I long for the day when I can move to a different place and have a bigger office so I can finally get a bigger desk... but that day has not yet come, so space is my biggest constraint.
My fallback is a Yamaha p-121, but I'd really hoped to find something that had octave shift buttons. I use them a lot for maintaining good posture at my desk so that I'm not awkwardly leaning when working on a tuba line or a flute line etc. (primary use is tooling around with VI orchestral composition)
I use a Korg Nanokontrol2 for sliders and I'm perfectly happy with it. My current midi keyboard is a Nektar panorama T6 and I'm considering lighting it on fire when I replace it because I hate its keybed THAT much. (it's actually in pristine condition, so hopefully I'll get some cash for it).