I don't own a buggy board, but I have seen them, and they look like a great idea. It would probably be a great way to go for you since your son is already four. I have a sit and stand, and I like it okay, but it is hard to navigate and it is very cumbersome. It is nice when your baby is in the infant carrier, and you want to spend a lot of time at the mall.
I also have a Bob Duallie Revoluition. It is WONDERFUL. I would buy it again in a heartbeat, but I must admit I don't use it all that often. I tried using it at the mall, but it is too big to fit through aisles, and it breaks my back getting it in and out of the car. (It also takes up a lot of space in the back of my SUV.) I just keep it in the garage and use it for neighborhood walks. It's great for trips to the zoo and arboretum too. I have yet to actually go for a jog in it, because my children will not cooperate!
Keep looking on craigslist or napervilleyardsales.com. I don't see high end jogging strollers listed very often, but it happens every once in a while. You have lots of time before the weather is nice enough to take the kids jogging. If you want to put the baby carrier in a Bob stroller, the attachments cost extra. REI carries Bob strollers, and every once in a while they have 20% off coupons. They have an excellent return policy if you have a problem with the product or just don't like it.
Good luck with your decision. This stroller thing is so hard to figure out. I own so many strollers and baby carriers and use them all in different situations. I sure wish I could find an all-in-one product.