I've got an even older machine that looks pretty much dead on the BES 916. It's the BAS416a.
Comparing the 916 to the 650 is kind of an apples and oranges comparison. It all depends on what you are looking to do.
Are you looking to transport this machine? The pr series is almost portable as far as embroidery machines go. The 916 will weigh about 5-600 lbs.
Are you comfortable with machines and can pay pretty good attention to detail without too many errors? The 916 is a commercial all the way machine. It's much faster and dangerous than the PR series. The PR series is built to keep people from breaking their machine. It won't let you strike the hoop, etc. The 916 will sew into whatever you put in it's way even if it kills it's self. As far as speed goes... the PR will get up to decent speeds but slows down considerably on different types of stitches. The 916 WILL slow down a little on huge satin stitches, but that's it. For the most time it will take about a second to get up to 1000+spm and stay there. MUCH QUICKER.
What size do you want to do? The PR series will normally sew around a 8x13 field. I believe that the 1000 will do maybe 13x13 or so. The 916 will do like a 16.5x17.5 size.
The pr series is much easier to operate. It's like they're both cars. The PR series is a corvette. It's nice and has all the bells and whistles, and it will go pretty fast. If you have one of these you think that you've got a nice race car. The 916 is a real race car, everything removed for speed and durability. More maintenance, but it does the job of racing much more efficiently but brutely.
They're both great machines. One much more friendly than the other one, but with the friendliness comes less actual sewing. Good luck on your choice.