I am sorry to hear about your experience. Sales person do not always have the depth of knowledge of the things they sell. And this is not limited to digital piano but many other things as well.
My own research led me to believe in slab form it's really hard to beat the wood action of Kawai in terms of overall feel and response. And people's search to improve one certain aspect (e.g. repeat speed) often leads to other actions with different compromise. Hybrid action is better but the price step up is a leap, too.
It's amazing your VPC1 is going strong for 4 years. Have you encountered any of the common problem that needs service? When I looked at the new-to-me GF action, I realized these things probably do need some maintenance to stay in top shape, and they are designed to be serviced more like acoustic actions. Maybe some simple cleaning of the capstan, verifying slip tapes remain in place, and maybe lubricating the key bushings is all you need to get the action to play faster or softer?
The ability to play pianissimo more easy and reliably is on my thoughts, too. VPC1 being a MIDI controller is supposed to be even better at that than my MP11SE. I know you must have experimented with the velocity curve in Pianoteq. If one has no concern about translating technique directly to acoustic piano, then I think tweaking velocity curve is probably a viable solution to make soft playing a little easier. On that note, I would like to hear from people who do play acoustic piano tell us about whether there is a "dead zone" in the soft touch where if one press the key with low enough velocity the hammer will not strike thus no sound is produced.