I would not worry about the head change thingy. If the bike runs out good then get it. I have a 2004 R1150RT now and used to own a 2002 R1150RT in the past. They all run rough but they run good. The 1150 engine just did not hit the mark for a smooth BMW engine. My 84 R100RS and my 07 R1200GS are both much smoother. But saying that I still love the 1150's. Like any beemer it seems the harder you ride them the happier they are.
84 R100RS LE,14 Ducati MTSGT, 73 850 Commando, 78 CT90, 14 Ural, 74 Eldorado police, 64 R50/2, 13 TR650, 01 DRZ400E, 94 900SS/CR