Pal is 576 lines
How are you dealing with making sure IR commands go to the correct sky box, if all are linked in via RF2? We've found big problems with intermodulation with multiple sky boxes since the digital switchover with the antenna signal having got stronger.
In terms of kit cost, your approach gives you more for less, but then the cost of getting your ducting in probably outweighs the capex of the matrix!
Fair play if your approach works for you and your clients. Personally, though, I'll stick with the matrix approach. We've had no problems with usability yet. We're using RTI remotes a lot at the moment, which means a single button press to setup the tv, matrix and source; then a common user interface regardless of the source being used.
Out of interest, what do you do with tight bends / corners in your duct routes? Do you include an inspection cover?
Chris