Mike,
I've had the copper and silver UNIverses side-by-side in my system. The silver was slightly slower/smoother on leading edges. It slightly rounded off initial transients. Some people find this sort of thing pleasant. I find it distracting. YMMV.
The copper is more neutral and has more lifelike microdynamics. It does not round off (or exaggerate) transient leading edges. Notes sound like what was cut in the grooves, neither more nor less.
I haven't heard a silver Airy 2 or 3 so I can't be certain this characteristic translates to those models, though I would expect it to. The Airy 2-X is already a somewhat gentle sounding cartridge. Gentling it more might really be too much. OTOH, the Airy 3-X is very free and powerful. Gentling it a touch could be helpful in some systems.
Whichever coils you choose, the SB option will yield a major improvement on a JMW. Strongly recommended.
Doug