I thought Merchant Republic wasn't compatible with empires of 6+ cities? Can you please explain how you survive the stability hit?
Merchant Republic will cause you a hit of a few points, but it will hardly cause your empire to suddenly collapse when switching to it. The proof is in the pics:
Republic of Spain - Tuscany & Aquilia conquered; working on Sicily & Malta (why aren't these at least OK for Spain?); Portugal & Azores annexed, Netherlands ganked at spawn and Ireland settled to serve as launching point for the Protestant purge in Britain:
Republic of France (More than double the points of my next rival in score; Frankish reconquest - Empire extends from Madrid to Poland, with Cordoba, Spain, Portugal and England as vassals - Holy Land and Iceland under my thumb - I got bored and tried to create a united Celtic nation by controlling Ireland, Scotland, Wales, Man and Lesser Britain - England still has Cornwall, though, but I have York as compensation - if not for my ridiculous British cities settled out to boredom, my stability would be higher):
Republic of Germany (history as Louis the German would have it - France, Burgundy and Germany united under one holy emperor; Lithuania & Hungary as vassals):
Anytime I'm playing an imperial Catholic civ, I build a church ASAP and run a priest to ensure a Prophet appears, at which point I found a knight order; after that I try to pop a Merchant or two to ensure a corporation later on (the Hanseads for coast and Medicis for interior are the best combo in my opinion, given the abundance of Fish, Salt, Fur and Sheep, plus Medicis produce pure gold while the others provides hammers or espionage - not as useful to stability).
Edit: I just realized I was running Limited Monarchy as Germany, not MR. All the wealth is due to Golden Age & running wealth in all my cities (I wanted to see how much I could produce in a turn - before the GA I was up to +2400 while still building buildings and units, but then Britain DOW'ed, costing me some Medici Resources - seriously, if you found a corp, trade for EVERY profitable resource from every civ you can and watch your wealth surge).