Disclaimer: I'm at home sick today with a terrible migraine so pardon me if me if the text in this review becomes incoherent at some points.
Per Dave's and many others advice, I decided that I would put down a relatively sizable amount of cash on a good quality soldering iron and donate my $13 Tenma iron. I've been studying some of the budget high-end irons offered from Hakko, Pace, OKI, and Weller, and decided to go with the OKI PS-900 as I got a really good deal on it off ebay and I wanted something with more of a pencil feel/short neck. I've also put a lot of time on a MX-500P and its by far the best iron I've ever used.
See model here:
http://www.okinternational.com/product_soldering/ps_900First Impressions:
The moment you open the box and pull the thing out, you know that you just bought a kick ass iron. Everything comes very well packed in a sort of OEM plain brown cardboard box. My iron came with the power supply, handle, coil assembly, stand w/sponge and brass loofah thing, silicon rubber pad thing, power cord, and manual. My iron also included a tip as well even though vendors say that it doesn't. I think the ebay seller that I bought it from probably threw it in there.
Power Supply:
The power supply resembles a black powder coated steal brick and could probably double as a weapon for bludgeoning someone. Its very solid and well built and appears to be very well sealed so you don't have to worry about dust getting in or spilling your beverage on it (it doesn't seem like an issue until it actually happens). Its very simple and rugged design. There's a power jack for the power cord, a jack for the iron, and an on-off button. I've come to really like this no frill design from using Metcals in the past. As long as the iron stays at a relatively constant temp, I see now reason for temperature or power adjustment and prefer not to ever fiddle with it. One other important thing to note, unlike the older Metcal's, the power supply is freaking enormous. Its actually quite compact, I think its smaller than the Pace ST70 and Weller WES51 even, and has a smaller footprint than the cradle itself.
I managed to open up one side of the iron without breaking the warranty sticker. I could only open up the back side as I didn't have a long enough screwdriver to get the front cap off. The guts are pretty much what you would expect, a bunch of big capacitors and inductors. I'm sure theres a microcontroller in there somewhere but I couldn't get to it without a longer screwdriver.
Handle/Iron:
The iron itself is rather pornographic, but kinda big. Using it makes me file like a midget or perhaps a leprechaun. The handle is fairly comfortable, similar to other Metcal's, although it would be nice if it had a rubber or neoprene grip instead of the ribbed plastic. The handle/iron splits into two pieces with a simple push of a button. One piece is the handle with the silicone cord and the other is the coil assembly which provides power to the tips, similar to the Pace intelliheat iron style. The tips slide on and off the coil heater very easily. Nothing to unscrew and they don't need to be yanked really hard like some of the irons of this design.
The tips seem to be of excellent quality as well. They don't seem to build up much oxidization at all and look like they will last a very long time. The more popular geometries are about $8 a piece from Allied. My one complaint about them is that they are rather big, diameter wise. Its not that big of a deal but I like the older Metcal style tips better that have a smaller diameter and are more of a pleasure to use for small SMD work.
Cradle:
The cradle is pretty nice. It appears to be made out of a molded/sintered metal and holds a big sponge and a brass loofah. It also holds three spare tips and provides an "auto-sleep" function which reduces the temp of the iron when not in use. I'm kind of confused by the big hole in the sponge though. I have no clue why it would have a hole in it. Maybe to fill it with water? I dunno.
Performance:
This thing is awesome. Like everything else with Metcal stamped on it, it heats up and is ready to go in about 5 seconds after you turn it on. I'm to lazy to measure it, but the soldering tip temp appears to remain constant for everything I've tried soldering so far. The majority of my projects are power related so soldering big inductors and large gauge wires has always been issue and had to be handled using my hot air station but I don't think I'll have those problems anymore. The thing is very comfortable to use and the handpiece puts your hand closer to the tip for better control over what you're heating. The fact that the tips seem to oxidize very slowly is a big plus too since they don't need to be constantly tinned like most cheapo irons.
Summary:
For the price tag of $250 retail and tip cost of $8-$10, the PS-900 is a dam good iron IMO. You get Metcal quality and performance at the price point of most professional budget level irons (Hakko FX-951, Pace ST70). I think the iron is a bit overkill for the average hobbyist and I'm not sure I still would have bought it at full retail price as I won't be using it on a daily basis. But, for a tool that I use probably more frequently than almost any other (except maybe a screwdriver), I think the price tag is warranted.