The current crop of consumer HD cameras are going to be quite a bit different from your NV-DX100.
Firstly, as the others have commented, most of todays camcorders use CMOS sensors, not CCD. And for less than £600 you're not going to find a camera with anything like the size of sensor (3 X 0.25" CCDs) you have in your existing camera. So be prepared for a hit on low light capability.
Secondly, as Andrew asks, do you really need CCD sensors? If you are intending to shoot footage where a lot of vibration (from cars, power boats etc) might be encountered than yes, you probably do. The 'rolling shutter' effects that come with CMOS sensors can be a problem in that area. (See here for a description :
CMOS Rolling Shutter)
If not, then no problem - CMOS sensors are fine for everyday shooting.
Many of todays cameras (again particularly sub £600) no longer have viewfinders -is that likely to be a problem for you?
Actually, when you look at the price of the NV DX100 all those years ago (about £2000 , IIRC) then the real equivalent model (allowing for inflation) is probably the Panasonic
AG-HMC151E - with 3 xCCD decent sized sensors (so good low light) and all the manual features you had on your DX100 (and more!).
But I suspect you're probably not wanting to go that far!
The 'top end' Panasonic consumer cam, the TM300:
Camcorders - HD Camcorders - HDC-TM300 - Awards & Test Results - UK & Ireland, does have a viewfinder and comprehensive manual controls, plus a decent sized 3 x CMOS sensor. That's likely to set you back about £800.
Perhaps that's more like the spec you were thinking of?
Although if you do want to stay with CCD sensors, and Panasonic, then it's either the SD9 (discontinued model, no viewfinder) or the HMC 151 (semi pro, expensive).
They don't make this easy, do they ?