Man I do not want to be an ####### but you posted this topic last week.
Personally I don't really see what the big deal would be in having a tub grinder if you are not planning on being a mulch company. What's mulch #2 worth $15 a cubic yard? And maybe you make 10 yards chips a day per crew. Which means you'd make $150 after you turned it into mulch, but I'm sure there's some loss, plus the labor, maintenance, initial investment and real estate (space). so multiply your 10 yards x 200 working days (a formula already proposed by someone else) that's 2000 yards of mulch a year sold for $15 = 30000. Someone competent enough to sell the mulch, process it and everything is going to run you 20k a year. Doesn't seem worth it, imo atleast.
Edit: Realized from the sig you probably have two crews since you have two chippers. So maybe you make 60k a year additional income. I suppose it might be worth it. But is where you'd be dumping closer than the dump or people calling in for free chips? Because I know where I work, time and gas is more important.