They are a good baler, with only two real issues to watch for:
1) The sledge assembly that holds the 3 large bale forming rollers will tend to wear on one side or the other where the belts run. If the belts haven't been adjusted properly over the years, you'll see grooves run into the frame. When these grooves get deep enough, the sledge will break in half. And it doesn't take many bales. The belts on my 664 weren't adjusted properly when I bought the baler, and I didn't notice the groove. It took about 5000 bales and it finally cut right through the sledge.
2) The pickups aren't as strong as I'd like. Watch the bearings on the arms that run in the guide race. They will fail eventually.
Keep the long 80H chain on the left side of the baler well lubed and adjusted exactly as the book says to. If it breaks, it often jams at the top, and its a bear to get out. In worst case scenarios, it'll break the top sprocket if your slip clutch fails to work.
As far as baling speed, its hard to say as I don't know your ground or HP. I've never run a 654, however I've only plugged up my 664 (same size throat, same baler design) 3 times in 5000 bales, and all times I hit a big wad of wet hay at about 10 mph. In normal cases, baling 2 ton/acre alfalfa, I'm comfortable running 10/11 mph with 120 PTO HP. I'm also rolling between 1500 and 2000 lb bales (depending on whether I'm selling the hay (18-2000lbs), using it for personal (15-1600), or custom baling (17-1800).
Rod