See, now you guys have perked my interest.
I spent last weekend baling my little 13 acre field with my JD 4520 (~3700 lbs, 53HP engine, 45HP at the PTO) using my neighbors in-line Case baler (Hesston design). It was the first time I had used my tractor (we typically use his Case, but it was broken down). I thought it worked just fine. Minimal rock-and-roll, I could control the baler just fine, and could feed the hay at a rate which, to me, seemed reasonable.
Based on this result, I am planning on picking up one of the JD model balers (328, 338, or 348) or maybe a New Holland this winter. I can't imagine there would be that much difference between the Hesston and John Deere balers that the Hesston would work just fine on my little tractor but the JD would require a 100+ hp tractor upgrade?
For example, here is a youtube video of a late model JD being pulled by a small JD cut, similiar to mine... Doesn't seem to be too big of a deal.
YouTube - Baling Hay
Let me know what ya'll think, but it seems to me the requirements for a small square baler might be over-exagerated by everyone but JD and New Holland (who both say 35hp for their low-capacity models). Maybe the folks commenting are just used to running through 100+ acre fields and just need the speed that only high-horsepower can provide.
Chet.