IMO if you have to choose between the slow lift with narrow access or the faster lift with a wider stance I would take speed over skinny every time. The speed will make you money every single day while the slow skinny one will cost you money and time every day. But you will be able to do those 5-10 narrow access jobs per year.
When I bought my first bucket truck I lost access to all those back yard jobs. But it was the best thing I ever did, because I made more money by utilizing the equipment and blowing out those front yard jobs. A friend of mine has a narrow access tracked Nifty Lift (only 34') and it is incredibly slow. For trimming palms on large properties it's faster to carry a ladder. Don't get so hung up on narrow access but focus on what can give you the biggest return. That means the lift with the faster ground speed and faster boom speed.