Sorry for the late response, been busy with other projects... so... by popular demand (?), here are the answers to the NL2X-NL2 quiz:
First, the repeated riffs files:
1.mp3: 2X 2 2 2X 2X
2.mp3: 2X 2X 2 2X 2
3.mp3: 2 2X 2X 2X 2
4.mp3: 2X 2X 2 2X 2X
5.mp3: 2X 2 2 2X 2
6.mp3: 2 2X 2X 2 2
7.mp3: 2 2X 2 2X 2X
Then using the same machine throughout, with backing provided by an E-MU XL-7, a Waldorf Blofeld and a Roland ep-77:
8.mp3: NL2X
9.mp3: NL2
10.mp3: NL2X and NL2, alternating, usually half way through each 8-bar repeat. (This was the trick one, as contrary to my description, I used both machines on this one).
Ok, not sure how much pictures will bring to the table, here the 2X is a guest on the dining table with my living room corner studio in the background, with the NL2 at top:

- Nordlead 2, Roland S-10 and Roland ep-77 in background, the 2X taking center stage in the foreground.
- NL2-2X-RW.jpg (367.22 KiB) Viewed 2630 times
An interesting thing is that although the keybeds are (reportedly) the same in both the 2 and the 2X, they feel rather different. Now, since I've put 10g weights in the keys in my NL2 to even out the action, it's not surprising, but the odd thing is that the sensation is that the keys on the NL2X feel shorter than the ones on the NL2. I wasn't expecting that. Both my friend and myself had the same sensation. The effect was so convincing that we even resorted to measuring the length of the keys just to convince us there was no difference.

- Measuring key length...
- NL2-keylen.jpg (108.21 KiB) Viewed 2630 times
The question is whether the difference in feeling can be attributed solely to the weights, or if the age of the machines make a difference - the keybed on my NL2 is more worn than Marlowes' NL2X.
As noted above, I did some A-B-testing on my own, and also at a friend's studio, who works among other things works professionally as a producer and doing mastering, and consequently has better ears than I do. He couldn't hear any difference between the machines either.
So the end result of this shootout is that I personally can't hear any difference in sound between my NL2 and NL2X. What I did learn though was that it is very easy to fool oneself - at one point I'd set the volumes slightly different, with the NL2X louder, and I quickly got the sensation that it sounded much better, until I took a couple of single notes and balanced out the volumes. The different sensations in keyboard response is another issue along a similar track.
I've heard of others who have said that they found the NL2X to sound 'cold' with the NL2 being 'warmer' and the original NL being warmer still. There might be some truth in this as I understand there are a couple of adjustments to be made in the DAC circuitry of the NL2 and NL, which could inadvertently be set 'off'. That would at the very least add a bit of distortion to the sound which might cause some machines to appear 'warmer' than others. Since I don't have the service manual for my NL2, I didn't want to mess around with an adjustment which would be tricky to get back to its original position. My NL2 has been gigged very little so it would make sense that the adjustments made at the factory still are reasonably within the original specs.
BTW, the Beatstep looks really nice on the empty panel space on the NL A1. I've been considering a Beatstep too, not for the Nord, but instead for my Blofeld which is not as well endowed as the Nords in the knob department. The sequencing functionality would then be more of a bonus for me than the main selling point.