You can still be money ahead if you follow the strategy of going to the more expensive places. Even with counter service there are deals to be had. There are some CS places that offer combo meals and they are huge portions and you can split those meals easily even with adults. CS meals are without sales tax on the plan, as well as, TS; so, that helps toward the gratuity on TS. It's like a hidden bonus.
If you or hubby are hungry then you can easily share the kids' meals, too; since, they are paying adult.
Now, the other side of me says do all counter service meals and you will be money ahead without the plan. You can order kid meals that way, too. Disney is not checking whether you have kids or not to order kid meals at CS. You will have more time in the parks; because, TS definitely takes longer. Also, you will still be money ahead I think even if you go to a few TS places. If you go at lunch for TS it's cheaper and you get most of the same entrees. You do CS for dinner this way.
I was on the fence, too. I ended up doing the plan, but I'm carefully picking out the places; so, I know I'll be money ahead on it. It's like a game to beat Disney on the plan. If I had three kids barely considered to be adults on the plan I think I would skip the dining plan; unless, you are doing the free promo. I think it would be torture to have so many TS meals; because, the kids don't want to stay put that long at Disney. You know your kids; so, you are best to judge their appetites and patience.
For break even, I think I would go for the plan, but it's still a time commitment to do it.