Even though your Premier just died, I still second Clay's thought on the Premier. I got one a while ago for test batches, and I am very happy with it. It runs for days without the slightest hint of overheating, hits particle size with no problem, and is fairly easy to clean. Also, I think that the 1.5kg volume probably refers to idli and dosa batters. In regard to chocolate, I don't think I've ever put less than 4-5 pounds in it, and I'm guessing you would have to get over 6 lbs before you had a problem.
And at $200 each, you really can't beat the price. Compare that to the Spectra 11 at $800 or the Cocoatown 12SL at $500. The latter two grinders can hold a few pounds more, but I think that this is more than mitigated by the fact that you can buy 3-4 Premiers for the cost of one of the others. Quite frankly, even if I had to replace the Premier every year or two, at $200 I'm good with that.
As far as getting something bigger, that just depends on your budget and your production needs. Three Premiers can produce 30-45 lbs of chocolate a week. Yes you use more electricity with three Premiers, and you probably also have a bit more waste. Then again, if you have one bigger grinder and it goes down (which is not uncommon believe me) your production comes to a halt. If you have 3 or 4 Premiers and one goes down, you only lose part of your production capacity. And you can get a new Premier from Amazon in a couple of days.
All that having been said, I believe Santha makes a 10kg grinder called the Spectra 20. If you're ready to move up to that level of production it might be worth looking into.