I also have several French gunners, that were given to me by a friend, which a fair number of us have been unable to ascribe to a manufacturer. As they are somewhat tall, and distinctively thin, I did not wish to integrate them into my Dixon/Foundry French army but, rather, have decided to convert them into Dutch.
The Dutch foot artillery 'may' have had shoulder straps, while the horse artillery had epaulettes. Cecil C.P. Lawson mentions a unit which was formed in 1793 by Captain Nacquard and comprised Dutch and French emigres. Not only did it give excellent service, later transferring to the British Army, but he reports that they had red epaulettes with white edge and fringe.
Mark Allen also directed me to a period drawing which shows what was probably their campaign dress, with distinctive hats and half-gaiters. The other paintings came from that excellent resource http://www.aldegarde.nl/napoleonicwars-5.html
ps. Would welcome comments on this subject, particularly on Dutch gun carriage paintwork.