I've got a Derringer card (@25MHZ) and I also wanted to change it to 50MHz. Someone at ebay put up two Derringers for sale at the time; 25 and 50MHz. I asked this person if there were any differences beside the oscillator. He compared he cards and answered that there were some parts different (can't remember which) but the 50MHz version did have better (read: made for higher clock frequencies) parts.
In the end, I didn't try it at all. The risk of frying a card like this... Maybe a little overclocking. But if I'm just too carefull, please tell me what's possible!
