You're talking about dry suits from two different worlds. Right now, Dive Right In Scuba is selling the Fusion Sport (Whites) for $1399; you will add at least a thousand dollars to that to buy a DUI suit, unless you buy used.
I've been diving Fusions for five years. They have a lot going for them -- they are inexpensive, do not require a custom fit for anybody, and are very hard to damage, at least in such a way as to make them leak. They have some downsides, the worst being that they can be difficult to get on over thick undergarments. You have to come up with a good strategy for footwear, which is easy if the socks fit your feet, and a bit more challenging if they are significantly oversized. The suits are VERY easy to dive (but I liked them better when they had SiTech valves on them). Customer service, back when Whites was Whites, was very responsive and good, but I'm hearing some different things nowadays. The SiTech user-replaceable seals are very handy, although the neck ring is a bit of a problem if you are very small-framed, because it makes it hard to reach across your body (or behind you).
DUIs seem to be hit or miss. I don't own one, but I know a lot of people who do. If you are not an off-the-rack size, you will need a custom cut, and that's expensive, and sometimes it works and sometimes it doesn't. Sometimes you send the suit back to California a couple of times before they get it right. They do eventually get it right, it seems, but that's really annoying in a near $3000 suit. The laminate suits often seem plagued with leaks, although the crushed neoprene doesn't.
If you are interested in looking at a suit in the top-end, expensive range, consider looking at a Santi. They seem to do a pretty good job of measuring and constructing suits that fit out of the gate, and I hear fewer complaints about leakage. (I will confess to recently having been made an extremely good deal on a Santi suit, which was custom, and fits like a glove. The jury is out on leakage until I get a few hundred dives on it
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