I work on projects on a pretty small scale (5 website, 1 or 2 of them need changes at a time -- some of them have 30 tickets, some have 3 or 4) and trello is perfect for me. If I fullscreen it I can get a good 'at a glance' look at everything i'm working on, and I have a colour code I use on labels to set the importance on projects.
I feel like trello has a certain tipping point for tickets :: at a certain point, its causes inefficiency. That being said, I felt pivotal tracker to be a bit lumbersome for my needs. I had to think too much / navigate the ticketing system.
I'd like to ask people who have used pivotal what thought think of it?