Saw an article a couple of years back which basically said, if you don't need a new roof then go with panels, if you do need a new roof, then there is not much in it and it then comes down to aesthetics. I wold guess it also depends on which way your roof is facing, if you are south to north then the north aspect is not going to be as effective as the south, so not sure if you end up with one aspect of solar tiles and one of normal tiles...
Saw an article a couple of years back which basically said, if you don't need a new roof then go with panels, if you do need a new roof, then there is not much in it and it then comes down to aesthetics. I wold guess it also depends on which way your roof is facing, if you are south to north then the north aspect is not going to be as effective as the south, so not sure if you end up with one aspect of solar tiles and one of normal tiles...