I think that in the right areas, the 4500/5000 is better than entry level.
From what I've seen, the zed allows better depth, inso far as it filters out the clutter and ground noise in my area to allow you to hear the signal that other detectors find difficult.
A really good operator with a 5k or 45 might be able to find find settings that can do similar, or even better, but for my level of experience, I can't work out those settings.
The problem is that up here, (Darwin) we get so much water on our gold fields, that minerals get washed into deep pockets, or down to bed rock level, the same area that the gold finds its way into. My mates with the zeds "see" them, but I don't. The SDC also does pretty well, but on small shallow areas. I have done well in some areas, but in others , not much chip, I really struggle finding bigger deeper bits, the zed boys find pretty regularly.
Cheers for all the replies, some great info here!