Neil...
Some personal observations / opinions:
I agree that pre-feed is a pain; it is, however, an effective means of controling the sudden jerk you can get if you haven't pulled enough material off the roll before you start. Effective or not, it's still hard for me to get used to.
I learned a long time ago that the speed of any cutter is not measured in inches / sec measured at the machine; rather, it's more practically measured on the weeding table and it's measured in numbers of successful, error free jobs cut / hour or / day. Speed is but one term in the throughput equation, and a minor one at that...as techman correctly observes.
And if you like thinking in terms of throughput, then you've got to consider whether you can cut certain materials at all...or how well. There was a cutter introduced several years ago advertised as the fastest plotter on the market, and so it was, too. The problem was, as many noticed, that the tops of 'T's sagged, the 'O's didn't close perfectly, the legs of 'A's and "W's weren't even, etc., etc. It didn't take long for the speed freaks to realize that having to do a job over made for a less than fast machine.
Maybe speed could be measured in Pounds...of scrap in the waste barrel ??