I try not to complain about it, but when I bought my 545 it was because I wanted a decent saw, and thought that it would pay for itself. Instead all that I ever did was fight to keep it running. The dealer did his best; he replaced the carb and top end, yet it still ran like crap. The only way to start it was to lock the brake, hold the throttle open and drop start until it finally caught. It wouldn't idle, and I would have to restart it multiple times while limbing the same tree. The day I finally rolled the tree on it I had caught myself dropstarting it twice without realizing the brake wasn't set; there are days when you shouldn't be running a saw. Yet I believe that it was a matter of time before I cut myself badly if I had kept running it.
Edit; after doing an internet wide search it appears that mine was the exception to the rule. Arboristsite & Forestryforum among others each have rave reviews. It makes me wonder what I was doing wrong.
How old you say that 545 was? sounds a lot like my old 550xp bought in 2013. After running my sons new 262MS today, I'd probably would've bought that instead of the 550xp.