I used a Scart/Composite/S-VIDEO to HDMI converter a few years back on a A600, worked great but I bought 3 before I found a good one and also used it for other gaming systems like Super Nintendi, playstation 1 etc.
But the price of the converter I used was near the price of an Indivision AGA and later I just used it for old consoles and bought Indivisions for my Amigas.
If you find a good converter the picture can be good enough but you can get a few crap converters before you find one good enough.
Do you have the option to use VGA on your TV? Since I have had quite good luck with a few VGA converters and they are cheeper.