I don't use such a circuit on my basses, but I do on my Strat Aerodyne. I actually did it 100% DIY so I'm rather familiar with the concept, now. It's both fascinating and far more useful than most people realize. Any guitar should come with one!
The "Rotary Varitone" on Ebay has a much rougher fit and finish than the Stellartone, but the higher selectable cap value of .068 can be a plus IMO, specially if you're interested in getting more punchy mids out of your pups. BTW I'm not even sure you'll hear any impact from the smallest cap (0.015). This will depend on the specs of your pickups (and your playing/listening audio chain).
Two caveats:
1. Works 100% passive so don't expect to put it in an active circuit!
2. The quality of the caps shown in the Ebay ad is suspicious. Personnaly if not doing it it myself, I'd rather wait for the Stellartone to be back in stock, unless in a hurry and motivated by the 0.68 max cap value. Then again, the "Rotary Varitone" is rather cheap...
Good luck!