I have a Franke single version in my needs-gutting kitchen. It is awesome! It's a really great seal and dates to the 80s. I will do it again. Don't know about the Kohler or the double, or how it works with a disposal.

Can't find it on the US site, but it's this:

Here is a link that might be useful: pop up drain thingy

Oh! it pops up? Not sure if that's what I want - would it knock over dishes stacked in the sink? Or maybe that wouldn't happen as it would only pop up if the sink had been full of water...hmmm....

It doesn't really pop up. I mean it does enough to drain but the strainer stays in place so it does all its business beneath that. It's all in the drain hole. If you move the strainer, there's a flat plug inside there. When it's closed of course it's down, and when you pop the knob thing it pops up enough to drain, but if you had the strainer still in place you'd not see a difference.

On my sink it's on the small side (disposal on big side) and I fill it up with stuff to hand wash and then when I'm ready to fill it with water I just tug the knob and start the water. Same to drain, whether I've actually washed the dishes or not. :)

This may not make sense because I haven't had my coffee yet.

It's really really good! I don't know how it would work with a disposal--I assume the Kohler one has that figured out since they sell the double. Here's a picture I happened to have uploaded of the button end. The soap dispenser didn't make it 25 years, nor did the faucet, nor the air gap (replaced since this picture), but that drain thing still functions flawlessly. These look kinda gross, don't they? If you want I could probably get a shot of the drain. But basically it looks and acts like a normal drain you'd never suspect could open and close remotely.

I had one in a previous kitchen and really loved it. I always wondered why no one made on for sinks with garbage disposals though. It does not pop, the little mechanism just opens and closes the drain assembly. You pull up to do both if I remember correctly. The mechanism does not really move it just activates the drain.

Good luck!

okay, I think that I get the idea now - sounds like a fun gadget!

Another question then - would you get a single one (on one side of a double sink) or the dual one (presumably one can only drain both sinks at the same time)?

I guess that's a personal preference. Surely that Duostrainer will operate each drain independently? And is it compatible with disposals?

I'm happy with it on just one side--I only plug the disposal side to bleach it out to restore its glorious pinkness and I use tongs to unplug it after that so I don't get all bleachy.

It is not compatible with disposals as far as I remember. They sell one for one side only.