Update - I bought the DeWalt D21570 on ebay, from a shop. £147 inc vat and postage, for a reconditioned one 240v (factory reconditioned - with 1 year warranty). They still have a 110v available as well, last time I looked. Arrived quickly 2 days. Also got a set of core bits went for Marcrist Turbolite. I seem to remember Marcrist have a pretty good name in drilling bits and diamond stuff. Came in 2 days as well, another ebay shop, paid £106 for the set of 5 cores. Very good value I thought.
Tried it out yesterday. Only a small core through an outer wall. Wow. Superb! That drill has a hell of a lot of power, you can feel the torque as soon as you pull the trigger. I love the shape of the drill, somehow fits in my hands far better than the normal core drill shape handle. This just feels comfortable. Drill feels solid and you can tell the housing is solidly built. Easy to change speeds as well, for the larger or smaller cores. Plus hammer mode. The chuck is 16mm and is enormous. Really lovely chuck. Its so big that it feels solid when you tighten it with the key, feels over sized, but I like that. Core drilled out faster than any core I've ever done. But, it was a small core and the drill bit was brand new, so not exactly a good test. But certainly not a disappointment. I'll try and remember to report back once I've drilled with the larger cores. The Dewalt has a nice solid feeling case and is actually really small in the case. Surprisingly so. My friends Metabo is a beast of a core drill, its enormous, this thing is more like a cordless drill. Another plus point for me, small tools are easier to cram in the car. the Marcrist also has a nice black case, with wheels and a pull out handle if needed. Though I doubt I'd ever need to use that. Its not that heavy to carry.
Paul