Nice.
I only have three flashcarts — EZ-Flash IV, EZ-Flash 3in1 and Supercard DSTwo.
I lost the 3in1 a while ago, but found it at the place I would have least expected it to be.
I got my R4 from some eBay-ish site. It was risky with what it was, but sure enough, the cart shipped out of China (I could tell easily by the packaging) and was in brand new condition upon arrival.
I think the Mister is cool and all, but honestly I have seen some video's exploring the difference between hardware and software emulation and the advantages of both.... I would pick software over FPGA, wouldn't mind some sort of hybrid approach but I can only imagine how complex that would be and how expensive.