I think that it must be emphasized that the mere fact that a figure is produced, there is no guarantee of it being actually representative of anything that actualy existed, nor that it is useful if it did.
They were mainly used as messengers, scouts, etc. "Habitants and Highlanders" gives you the option to deploy up to 6 in the St Foy scenario, with the admonition that they were such a small force that they will have no effect on the battle, and you are silly for even thiking of using them.
So, I did, and they are right. The unit is too small.
However, the RAFM figures are relly beautiful castings, in a "true 25mm" scale, so a bit smaller than the 28mm and taller giants out there now. Its uniform is also pleasing, a blue coat with red facings and a Kewl bearskin. All the Cool Kids wear bearskins.
Officers, by the way, came from infantry regiments, and retained their regimental uniform.
I have also used them as dragoons in skirmish games, harrassing poor exiled Jacobite Scotsman who want nothing more than to get the uisgebeath back home, on which they have paid no duties.
Their most realistic use is as scouts, messengers, convoy escorts, that kind of thing that 18th C light cavalry were used for.
Battle cavaley? No.