While I haven't taught maths using smartboards, I have been taught some, so my experience with that may still be relevant to you. In my case it really was a board, which the lecturer writes on in the same way as a blackboard or whiteboard - I'm not sure if some things might be a little different with a smart podium.
Overall, my experience of it was not particularly positive. The board seemed to be very difficult to write clearly on (all of the lecturers I had complained of this) and having seen two of the lecturers give talks with a blackboard I can be sure that the board itself really was making a difference to their handwriting. This is something that might be better on a podium, but you should probably try one out to see.
The other big problem is how little you can see at any one time - the amount that you can write on one "slide" on the smartboard is already less than can be written on an average sized blackboard, and we could only see two pages at once (this already requires two projectors and some setup - the default situation is probably only being able to see the page being written on). If you were using the blackboards in the room you describe I'd guess that the audience could probably see at least half the lecture all at once, which is much more helpful.
In our case, the reason for the smartboard is that the lecture was being broadcast to five institutions simultaneously (including the one it was actually happening in), and using a smartboard was the easiest way to transmit the content of the board - the video stream had too low a resolution to be able to read from. Unless you want to do this, I'd stick with the black/whiteboards.