Shindo advice

I'm looking to upgrade from my long-time pre reference, a Joule LA200/ops-1, and have settled on a Shindo - either a Monbrison or Masseto. My question has to do with a lot of people I see on audiogon moving from the Monbrison to the Masseto, and fairly quickly. The obvious answer would be that they love their Monbrison and just want more. I know one can not go wrong with either, but we all know that there are sweet spots in every designer's line and I'm just wondering if its also because the Masseto is a big jump rather than an incremental one. Just curious.

Would also like to hear some more opinions on differences between Monbrison and Masseto.

Last,any opinions about me digging around for an older Catherine?

To get an idea of who I am, I run an all SET/nos tubed system with a TNT4/Graham/Cardas Heart analog rig. I sold my main speakers and am looking around, using my backup Spendor LS3/5As for now. Past speakers have been Quad US63s and ESP Concert Grands.

Thanks for the help.