I get it. It's hard to justify spending a lot of money on something that isn't used much, and that cost difference is substantial. After a few more jobs this summer the Del Morino will have brought in more money than was paid out for it, but it's going to take a lot more summers before I can say the same for the RC3712.
I don't buy an implement with the idea that I need to do work in order to pay it off, but if that's an option then I feel even better about the investment. I know people who pay $1,500 or more for snow removal each winter. I've never paid for snow removal, but it didn't take more than a few winters before I was at the break even point based on the cost of the front blade and blower. But it's the convenience and independance of doing one's own snow removal that appeals to me more than the need to "pay off" equipment in my head. The latter is just icing on the cake.
I look forward to hearing all about your flail and how it works for you. I hadn't realized that your tractor was such a beast, but it sounds like you're more than prepared to run the flail, and to make any needed repairs.