The main thing about carbs is that they don't like to sit; they gum up easily. If you use them regularly, they work just fine. My M900 was a daily driver, so I rarely had problems with it. The original carbs wore out and had to be replaced at 185K. I got a set of used carbs with about 30K on them, and used them for 80K, so those had about 110K on them when the bike was mashed, and they were still working fine. Once you get the hang of using the choke, they were fine for starting and all. I had to upgrade my starter circuits for the colder seasons; stock it didn't like to start below 40F (5C). But once I went to 4g cables, and added a dedicated ground cable, then as long as the battery had a decent charge it started fine down to 20F (-7C).
1993 Ducati M900 Monster "Patina" (265,000 miles, killed by minivan 30Oct17) -- 1995 Ducati M900 (wife's bike) -- 1979 Vespa P200 (daughter's scoot) -- 1964 Vespa GS160 (160cc 2-stroke) -- 1962 Maicoletta scooter (275cc 2-stroke) -- 1960 Heinkel Tourist 103A1 scooter "Elroy" (175cc 4-stroke)