The 100Hz compatibility may be limited, as many 100Hz sets now use all sorts of processing to reduce line flicker and motion judder. You most likely must be able to switch the TV to 'raw' 100Hz mode for the gun to work. Even then, the gun may not work as precisely as on a regular 50Hz TV.
To be honest with you I've yet to try my PS2 lightgun games on the Tosh Strata... I'll try out my DC though and HOTD2 when I get time and get back to you with the results. I've been rather busy recently and haven't posted here for a good few days so just give me a day and I'll be back ^_^
It ain't the 100Hz its the digital sampling nature of the set introducing a timing mismatch between what the gun is seeign and what the console is putting out. Theoretically you could make a gun that calibrates itself to the TV but and this is a big but it would have to be pretty accurate and I doubt this is possible for lightgun prices. I'm betting this gun might have th eright sort of delay compenasation for certain models but its going to be very hit and miss ( pardon the pun).