did you try what happens if you select it as the main source and set it to favor motion instead of sharpness.
If you manage for example to get a higher fps via that? If you take a candidate like the 6000 mxp and you
do not get it it might be quite sure that its 15fps max. On the other hand if you get it on it or some other system
you answered your question yourself :-)
Think I remember something with the 15fps on dvi at least on the first gen of 3000 mxp which only supported non hd cameras.
If they need more, maybe jabbervideo or a sx20, ... would be an option?