If you want a head that will cut close and feed great as mentioned above talk to Young's Custo Ag Service and get a modified 20' 820 from them with an Orbit reel.  We demo'd one of their 22.5' heads side by side with a neighbors 25' 1020 (a one year old head with Field Tracker) and that 820 out cut it enough that I could see from the road where each head ran.  We ran several stock 820s before that and they pretty much sucked but after Young's work their magic on them you'd swear they were a totally different head.