I would pay more for a watch with the original papers because that, for me, is the icing on the cake. I cannot comment on the deal without knowing when the watch with papers had it's last service, how old it is, what the price difference exactly is OR what a rehaul would cost Questions!!
Would be to buy some different straps for it, each and every strap will give you that 'new Patek' vibe and you will find out that the 5212 is a very versatile watch. Enjoy it for a year, and if you do not feel it by then... put your money in aother watch