I've never had a hobby that gave me a case of G.A.S. like coffee has.
The Vario is great. If you bite the bullet, you won't regret it. I've already been able to try a wider range of coffee with it, and that alone made the upgrade worh it. Until I bought it, I was forced, like you, to limit myself to coffees that worked with my Virt, given the limited adjustability. I've never used a Proline, but from what I've read, they're in the same league as the Virtuoso, and they bring the same frustrations.
There are ways to improve grind quality and adjustability without spending so much. There are a number of good espresso grinders within the $200-$250 range that would be far more suitable than the KA. Ascaso/ Innova makes a number of stepless grinders that supposedly produce a grind quality on par with the Vario. The drawback is that they're not as rugged or convenient to use as a Vario. They're also not suited for other brewing methods.
Another route is to try and pick up a used commercial grinder. I almost had a deal on a Macap MX for $250. If you keep your eyes open, you can snag one off eBay. It'll likely need new burrs and some modification to be suitable for a home environment. However, you need the counter space to accomodate a big grinder. (My wife was relieved that the deal fell through. I might have been drinking espresso in the doghouse.)
For me, the Vario was the best choice. It cost me more than I'd hoped to spend, but so far that's been the only compromise.