It depends on how much walking you would be doing, and whether a double buggy is affordable to you at this time. Phil&Ted is the only worthwhile option for siblings that are not twins, and Phil&Ted don't come cheap.
Just like you, I had a 2.5 year gap between my two kids, and chose a buggy board for pragmatic reasons. I thought that I won't get a lot of use out of Phil&Ted beyond the first six months or so, plus I would have to get rid of our existing buggies (Silver Cross pram, Out-N-About sports buggy and a compact Maclaren pushchair, all of which I loved) to create space for Phil&Ted.
We bought a second-hand buggy board for a £10, and used it to walk to the nursery (15-20mins distance), and it kind of worked, but was quite hard some days. As a parent pushing the pram, you don't really walk 'normally' with a buggy board, you take up this funny kyphosis posture, and just as you've developed the right kind of grip, the toddler is no longer interested, so off he goes and you keep pushing the pram and banging your feet against it. At this point you stop, and put the buggy board up (some models allow this), but your toddler - so obviously disinterested in the buggy board just a minute ago - was actually spying on you, waiting for you to put the buggy board away, so that he can now request it back down again....
Walking with a toddler is by definition a test of your patience, so I'm not sure whether blaming the buggy board is fair though 
On weekends and special occasions, when we were going out as a family, we took two buggies (a pram for the baby and pushchair for the older child), for quite a while, and it was bliss.
If I had my time again, I would have made the same choice (buggy board), because £300 was just completely astronomical expense for us at the time (we bought our other two buggies and the buggy board second hand, and sports buggy was given to us for free by a friend, so it was less than a £100 for the whole lot).
However if I could afford it, I would definitely, absolutely go for Phil&Teds. Mother's sanity when the kids are very young is worth an awful lot, and it does make your first year with the new baby a lot easier!!!