For a few months now I've had a Meris Mercury X.. I definitely give it a thumbs up for synth usage.
In a nutshell it has the spacey/ambient reverb algorithms of the Mercury 7, plus the traditional ones of the Chase Bliss 1978, plus a few more... not to mention all of the other modulations and dynamics FX you can add.
Sounds incredible!
It's actually much more than just a reverb pedal, it's really more like a programmable multi FX unit. On the surface that may not be an attention grabber, but what's brilliant about it is HOW you program it. The UI design is such that you can achieve your goal quickly using the knobs once you've wrapped your head around how it works (which only takes a few mins).
It's not an inexpensive pedal, but considering what you get I believe the price makes sense.