To make use of the speedbooster both the router and the wireless card have to support it. But if you have any cards on the network that don't support it, I think the whole network has to come down to their level/speed. (I haven't tried it myself.)
I'd personally go for the GL. Speedboost isn't all it's cracked up to be, it's noisy (causes problems for other networks nearby) and like I said it would only work if both card and router support it.