Vandersteens and subwoofers other than the 2Wq?

With the Vandersteen's, I would go with the 2Wq. It is designed to mate perfectly. Why did the REL stick with you more? You really shouldn't "Hear" a sub. It shouldn't increase the loudness, it should only allow for the lowest octaves to be reproduced. Setup will play a bigger part than anything.
The REL is a nice sub and should mate with the Vandersteen's if you want it to. What I would listen for is does the tonal qualities of the REL reflect those of the Vandersteen 2Ce's. Also, the Vandersteen sub is 300 watts vs 100 for the REL and uses 3-8" drivers instead of a single 10". Also, with the Vandersteen Feed Forward Error Correction using a 80 hz crossover, you cannot dynamically restrict it and/or cause distortion.
With all that said, the choice is ultimately yours and YOUR listening preferences. Need to try both and see what works for you using the 2Ce's with each sub.

You can change the crossover "Hinge" point by adjusting the value of the capacitor in the crossover vs. the input impedence of the amp. Using the formula 6.28 x input z x crossover frequency, you can adjust for whatever sound you want by allowing the main speakers to operate further down in frequency or up in frequency. For example, if you set the crossover at 80hz and then re-adjust say at 70 hz, the sound will be more bass heavy. If you do the opposite and go from 80 up to say 90hz, the sound will be leaner. You can always adjust the level control on the sub to compensate for some of this. The 2wq error correction is designed to exactly match the rolloff of the 6db filter at 80hz with a boost in exactly the same fashion creating a flat frequency response. However, room acoustics affect this considerably. That is why Vandersteen says try a value above, equal to and a value below. Since the lowpass on the 2wq is non-adjustable, this is the only option you have. In the owners manual, it shows this. The boost created by the "Error correction" remains the same. You just adjust the crossover point for the sound you prefer.
I can't imagine with some effort not being able to make the 2wq work in any position.
One of the problems the 2wq corrects is the phase shift created by faster slope subs. This was designed into the error correction based on Vandersteen's trials. Everything is going to be a trade off of sorts. But with a little patience and an open mind, you can get this bad boy to work!