I grow Lapins in Ohio. Flavor is very good. Not as firm as Bing, but I would still consider it firm. Planted in 2014 and was productive this year. It has been through at least on brutal winter. (appx minus 15 degrees). It was from Schlabachs. They say their semi-dwarf cherries are on Krymsk and are 60% of standard size. Raintree has Lapins on Gisela 3. I think that might be worth a try. I would guess that good drainage might be even more important for such a dwarfing rootstock. I recieved a Surefire tart cherry from them on Gisela 3 this spring, but all I can say is that it looks good so far.
Here are some actual pictures of my Lapins this year: