The only issue I could see is wages. Keane is on something like 80k a week at Spurs and we have a wage structure that couldn't accommodate Yakubu at 40k a week. We know Top won't break the wage structure and they have said they won't be held to ransom over player's demands. Something also tells me that it'll be very hard to persuade Keane to take a 50% pay cut. Sven has said himself that this '20 goal a season stiker' is someone they'd LIKE to have but not really someone they NEED so I doubt the wage structure would be broken.
If we can get him to agree on wages, I think he'd be a very good signing - someone who's proven to score goals and someone who needs a spark in his career and a fresh challenge and this could be it. Certainly if we could give him a run of games (something he hasn't had since Celtic) then I think he'd get 20+. Don't think he's past it, his recent performances at International level have shown that, and in the Championship I think he'd definitely be able to do well. As I said, I just feel he needs a run of games and a new challenge to re-ignite his career.
Would prefer him to the Yak. Keane will work harder for the team and he is always looking to play on the shoulder of the defence and run in behind and stretch defences which will come in handy when teams come and park the bus.