The following articles have been posted before, but will post them again. They do address some of the pros, cons, and issues, particularly the issue that many three carb set-ups will NOT fit in all vehicles:

http://www.thecarburetorshop.com/Dual1barrelcarbs.htm

http://www.thecarburetorshop.com/Triple1barrels.htm

The way I personally learned about adjusting multiples AND the "book" to which I earlier referred was on my own TR-3 in about 1966. I ordered the *&^%$#@ book and proceded to attempt to adjust the carbs. I got the carbs so fouled up the engine wouldn't even run! Fortunately, I had the good sense to back out all the "adjustments" and readjusted everything to factory specs. SURPRISE! It started and ran pretty good! I grabbed the book, and drove the car to a dealership; and paid good money to get laughed at! But the money paid was worth it; as the old mechanic who set the carbs showed me how, and explained that the book was just exactly backwards; and by using the instructions in the book you always got the front carb too lean and the rear carb too rich, which is exactly what I had accomplished.

Reading is good; but sometimes it gets a novice in trouble. Having a mentor is MUCH better.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop