I have replaced a Burisch with a Kalkhoff Groove, they are quite different in quality, not that the Burisch is too bad, just that you end up tweaking bits to get it right. Two major things I had with the Burisch were eating cassettes and the full power assistance, there was no gradual build up. This was great for my commute, but less so when I was out for a ride with my wife and son. Forks and brakes were good on the Burisch, just bear in mind adding a rack, mudguard etc all add to the cost. The Groove (and I know it's not as good as the Impulse bikes) is really well built and very light. Battery range is good, though the pull of the motor is not as strong as the Burisch's. The brakes are surprisingly good for rim brakes.
Another thing to consider is the support you get Burisch require you to return to their warehouse, however 50Cycles are not too far from me in Shoreham. As others have said if you can try and ride both.
John