Funnily enough I was thinking about this the other week. The thing with Saha is the way that his injuries impact on his form. My impression of him at Everton was that when he stayed fit and had a run of games, he was still as good as any striker outside the top four clubs - he had a number of golden patches for Everton when the goals were regularly going in and he was a real star. But before too long he would pick up an injury and when he came back from one he always needed a run of games to get back up to that level. If you could guarentee the fit-and-bedded-in Saha, he'd be perfect for the way Jol wants to play. My worry would be how many games he missed and (more dangerously) how many games he would need while building back up to optimum performance levels, keeping other players out of the side as he did so. If Jol wants to play the 4-2-3-1 or similar, that means not having a striker that we can expect any reasonable return from for several games. There's a joke to be made there about AJ/Zamora/your scapegoat of choice, but I'll walk tentatively around that one.
Some kind of pay-as-you-play deal might work, but even that wouldn't get round the problem of building him back up after each injury. It would be great to see him back, but I suspect it would be a mistake.