+1 sold my TVC immediately after hearing the Tortuga
That's awfully bold. I'm not convinced the TVC isn't better, but that doesn't mean it's the preference. The Tortuga uses devices that have a dab of capacitance. I think they sound great when I've used them as resistor replacements.
Anand, that's a bit sad, because relays introduce their own thing, too. I'm not saying they can't be good, but it doesn't come too easy. The Tisbury uses my favorite little attenuator from China, found on eBay. For the price they just don't have competition until you're well over $100 for just the attenuator piece. They are not perfect, but you can't beat them until you really start to spend some $.