MiST definitely needs scaler daughter board.
Recently i've bought Amiga 1200 and then so-called flickerfixer: http://amigastore.eu/en/194-indivision- ... ixer-.html
This is, actually, scaler supporting wide range of resolution and scale+frameconvert to correct HDMI/DVI/VGA resolutions. It sits on one of Amiga chip and gets all required signals. It's lucky that Amiga uses PLCC chips and thus allowing such piggybacking mods. For MiST it will be harder, but still doable i think. It either can get signals from VGA resistor array, or if possible from fpga pins directly.
Lack of HDMI output is my biggest frustration from MiST. MiST author asks to use some strange monitors supporting non-standard retro modes. But if you want to use standard modern TV with HDMI or projector, then you have no options.
And using external scaler is not a good idea by many reasons:
1) external scaler has no idea about pixel clocks, thus you will have distortions when some pixels are wider, and some are very narrow.
2) external scalers usually made either only for old TV resolutions, or VGA-only. I didn't find universal scaler/converter supporting both. And in retro video both TV and VGA are non-standard, so you can expect a lot of problems even you will find some universal (usually crazy-expensive) scaler.
3) external scaler has to guess the parameters of video and sometimes misses, making video look ugly. non-centered, etc..
Those, who may be looked at OSSC - forget it. It's a rubbish. Waste of money!