Just to add a bit of information. Travel Supreme did offer the mid-engine chassis for a couple of years but I believe they only had it in a toy-hauler not as a 'family model'. As you updated, Newmar offered the floorplan you are describing. They had the 3950 and 3951 for 2007 and 2008 and then had the 4159 in 2009. Unfortunately they didn't sell very many of them (I've read they only build 3 4159s) so are a bit hard to find. Also depending on your requirements, they appear to have very limited exterior storage.
One complication if you are searching for one is that Newmar offered the 3950/3951 with or without the loft (not sure why they didn't just make it a different model number) so you have to filter them out manually. Also some sellers simply list them as 'All Star' or 'AllStar' some list is as 'loft' or 'family' model so you have to have a pretty broad search to find all of them.
Personally, I think it's a great floorplan and really wish other manufacturers would offer something similar. But, for us, it was a fairly high end coach so even used, the prices are quite high and I don't know if the storage available would be sufficient for our needs.