I used 1685-1845 for a number of years when I was a teenager (Tony Bath, right? Mine was a green cover), and I must admit I had a lot of fun with them... mind you, WRG was the rage at the time and I was merely following suit along with the rest of my gaming buddies.
As a set of rules, they are v-e-r-y precise. i.e. they will usually give you the results you would expect from a combat of that era; but not much room for lee-way as they want you to follow tradition and do only what is expected of you (try to think and fight like a commander and his men at the time would have done). The results will usually end up pretty much the same every game, as there is not much manoeuvrability for `fun` or experimentation, and as they are old school, so there is little provision for solo play if (like me) that is something you enjoy doing.
1685-1845 can also give some pretty weird outcomes if you try to deviate from what is expected of you.
Basically, the rules work on the assumption you like the minutia of military history and want to re-enact and stage things in a way WRG view history; I always had a problem with absolutes and moved away to more flexible systems as I got older... namely my own lol.
Nice tidy set of rules; but I think they have been overtaken by time and 21st century thinking and new knowledge of the genre makes them a touch dated, in my honest opinion. At the time of WRG, the world was a smaller place (no computers and more innocence) and people tended to swallow what they were given by the experts without question.
As for imagi-nations, I`d advise you join: http://games.groups.yahoo.com/group/SOCDAISY/?yguid=321235886
the emphasis there is on simple rules yet lavish suggestions for expanding Lace Wars etc into full blown campaigns, uniforms, ideas, blogs, and solo enjoyment etc etc.