Dude! I don't know how much help I can be on this question as I've not really owned many metal detectors. Well, I have had a few, but only two "good" ones. I've had several cheapies over the years before I got serious about this hobby. Radio Shack $20 variety.. Oh sure, they worked, to some degree, but they weren't very sophisticated or even reliable. More recently I've owned a Bounty Hunter, again a "cheapy" of sorts, a Wal-Mart special.. litterally! This model was specially made FOR Wal-Mart I found out later. It's more of a serious metal detector than others I've had before, but it's not very user friendly.
Today, however, I have and USE a Whites Metal Detector. A Prizm IV model to be precise. This machine is VERY reliable and VERY easy to use. Straight out of the box Anyone can find stuff with one of these. I was detecting coins 15 minutes after my detector arrived at my house, and it only took that long because I went to White's Home Page to view some instructional videos. <grin> I probably could have just gone on outside and started finding coins and stuff as soon as I assembled the machine. I *did* find stuff right in my own back yard. A place that I'd already "detected" with the Bounty Hunter and couldn't determine if the target I was picking up was a coin, a nail or tin foil, or whatever. With the Prizm I could see what the coin "probably" was and how deep it was. COOL! The discrimination modes let you determine what you will "hear" or pay attention to while detecting.. the machine does all the work for you in that department. Oh, and as far as weight is concerned?... The Prizm line is VERY light, right around two pounds or so I think.
One thing I WILL recommend, however, is a pin pointer. White's offer a "Bullseye II" with most of their detectors..they come free with the purchase of a detector, or can be purchased separately for a little over $100. Let me tell you, if you've never used a pinpointer in conjunction with a detector, you really can't appreciate the addition of the Bullseye. Once you *HAVE* used one though, you will swear by them for life! No matter how good you are or get in locating a target with your detector, its only "close" to where the target is.. with the pin pointer like the Bullseye you can zero in on that target. Often, if the target is near the surface (say 2 inches or less in grass and soil) you can get to within an inch or less of where the target lays. Instead of digging a big plug, you can often just pop out the coin or target with a probe or a pen knife (pocket knife). Sand and loose soil can be difficult to locate a small target in even if you are right on top of it with just a detector.. especially if the coin is discolored (black) or clumped up with dirt or whatever. Sifting with your fingers might find it sometimes, but the Bullseye rarely if EVER misses. I tend to use the vibration setting myself.
So there you have it, my detector preferences. A White's Prizm IV combined with a Bullseye II pin pointer (never detect without my Bullseye! <grin>). I hope I was able to help. Happy Hunting!
Frodov