This is a great thread, I was having the same dilemma for the past couple months.
Personally, I'd go with a dump trailer. I'm currently in the market. If you do go for the trailer I'd look for something bigger than a 10 footer. I'm looking for a 7x12 for myself.
Less maintenance, you can use it as a dumpster, haul a skidsteer in it, you could raise the sides of up to 4ft if you wanted which on a 7x12 would be enough to fit 12 yards or so. I have a similar truck setup to you right now, 2500 chevy and no dump. Having one more truck to maintain and insure could turn into a pain in the arse.
To be fair, the pros of having a dump truck that I considered, besides what was already mentioned about having to tow the trailer, is if you plow snow, or need a back up truck for any reason, you'd have one. But to answer your question, I do see a dump truck as a greater expense.