Sorry to kind of hijack this thread, but it seems like a good collection of MetCal users. I've never used one and trying to figure out the advantages and disadvantages of going with one over my current station, Hakko 951. We are looking at getting two irons for fairly mundane TH production work, and upgrading my prototyping iron.
For those of you who have tried normal sensor controlled, what is better on using a MetCal? Do you find the quicker RF temperature control making a large difference on soldering action?
The Hakko 951 is really quite good, I don't think the price of a metcal would be worth the upgrade.
Times you notice the difference;
The first few joins; hit the power switch and by the time you have the iron in hand and the solder in the other and are at the part, its ready to go.
Med-large joins that take more than a moment to flow but less than a few seconds; Most irons have a bit of a "dip" in temperature for feedback between the tip tip and the heater - small joins are no issue because thermal capacity and massive joins are no issue because the join takes long enough to flow that the loop is already flat out.
Idle time between placing components/adjusting the board; the iron idles very quickly and comes up to temp very quickly so there is no delay there.
Aside from these very specific times you won't notice a difference at all, the Hakko 951 has the heater and temp sensor built into the tip so it is already very good, much more so than the 888.
On the topic of the OP, basically, we can conclude;
You will probably need more than one cartridge.
You probably won't need more than 3.
Cartridges that have their tip extended out from the body are best for everyday use.
You only need a fine tip if doing fine work, but since you're doing TH stuff, a STTC-137 will probably do all-round.
Other companies make Metcal compatible tips - Thermaltronics (who are owned by OKI) and EasyBraidCo both are authorized to make tips.
The other tips can be cheaper (i'd also like to add), and second hand or new-old tips even cheaper again!