I have a Britax practicale and DS1 goes on the buggy board with it. It's a wider type bugyy board - think it's called "Kiddyboard" He fits underneath the handle IYSWIM. My SIL has a fairly ordinary fold up stroller type buggy and has the long thin buggy board which fits on there fine. I think most pushchairs will take a board!
word of warning, the mamas and papas aria does not accomodate a buggy board as i found out. when buying your pram take into account the handle as after a while as they get bigger, if the handle is in one piece or 2 handles curved in your childs head may not fit.
OK I know you said not MacLaren, but MacLaren XT plus buggyboard was a dream. XT goes flat for baby, and there are pockets in the back of the hood for the toddler to stash drink/snacks/toys. Also the XT isn't that heavy (and you do notice that you are puchsing the wait of 2 children!) I think that the only downside was that it was difficult to apply the brake with the buggyboard on, but that never bothered me.