I just can't imagine doing tree work without a chipper! (50% of my work is pruning)
90% of my work is pruning; yet, I would gladly operate without a chipper if I had a free place to dispose/burn brush closeby my market area. As I do not have such a location at my disposal, I am forced to buy a chipper because it will be more economical than driving 10miles one-way to the landfill each time my dump trailer is full of branches. I love chippers (as I do all tree care equipment); however, for smaller operations, there is a definite downsight to owning/operating equipment - MAINTENANCE! I would rather operate with a low-maintenance dump trailer than with a chipper. That said, sometimes equipment is necessary - you just have to run the numbers and use your past experience and business records to justify each equipment purchase. While one tree guy might be able to make a profit off of using a chipper, another might actually lose money using one. I've been in both positions and keep changing my equipment lineup as my market and business needs change.
There is no perfect equipment and labor setup for all arborist/landscapers/contractors, etc. Everyone has to figure out his or her market, his or her overhead and apply those factors towards deciding which equipment will bring a higher net profit at the end of the year. Mind you, I said NET profit, not GROSS - the number that far too many guys get hung up on when deciding what equipment is needed. If a chipper costs you more in bank payments, maintenance, operating costs and depreciation than running a dump trailer and pickup would (taking into consideration, of course, extra drive time to dump debris and extra fuel for that drive time) you'd be better off just running a dump trailer and pickup. If you can show the numbers that justify the chipper purchase, then let the numbers speak for themselves but, don't go buying a chipper just because someone else says he couldn't operate HIS business without one. Is your business EXACTLY the same as his...?
Easy way to crunch the numbers is extimate how much time, disposal fees and fuel you will save by operting a chipper vs running dump trailer loads to a landfill. Then figure out what your annual operating cost will be for a chipper including bank payments, maintenance, fuel, depreciation, etc. If the chipper doesn't make you money over running the dump trailer, then you have to decide just how badly you want another toy to maintain - because, if it's not making you money in the long run, then it's just another big boy toy and it's not so much a business justification for buying one as it is personal gratification...