Whatever actual fee is received GH will put a spin on it, so that's a side issue. The question is do we want a player to return in a key position who may again decide to either get himself in trouble off-field or simply go through the motions and not give a monkey's for whatever reason.
IMO we need to move forwards, and I think GH has said as much. I also think some of the quotes from Hardaker whilst in Oz (making out the long-term deal with Leeds was some kind of serfdom instead of something he negotiated and was probably pretty happy with at the time) would put GH off, not to mention all the extra hassle he's been in his time at Leeds.
Hardaker clearly wants/wanted to stay in Oz, but his performances this year were really average. He certainly wouldn't justify a big wage and any club that took him on based on this year would see him as a squad filler. I've said that maybe with a full off-season and lots of effort (including adding some serious weight without losing speed) he might go well, but he's hardly likely to be offered much in terms of wage, at least for the first year. So it wouldn't surprise me if SL is his only option.