Quote Originally Posted by peety3
The 17-55 is not a truly durable lens - the IS unit has "issues" after being handled a fair amount. Both times I've rented the 17-55, it's had a jerky IS unit (and both times, LensRentals has taken excellent care of me).

Lensrentals.com's failure rate probably not the best way to judge lens durability. Granted, the fact that they stock >50 of them gives them good experience with the lens. However, they stock >50 of them because it's a very popular lens, for a reason. In general, rentals have a significantly higher failure rate than purchased products - they are transported more frequently, and used by people who don't have a vested interest in protecting their investment (especially since the damage insurance is relatively cheap to add). The 17-55mm is a very well-built lens. No, it's not L-quality build, despite the L-quality images it produces (and the L-like cost).


The OP has a 400D with a kit lens (18-55mm). It's hard to imagine a less durable lens than the 18-55mm kit lenses, with their plastic mounts and low/mid-grade plastic barrels (maybe the 50mm f/1.8 II comes close). Point is, if the OP has kept that lens in usable shape since buying the 400D, the 17-55mm will hold up just fine.


Quote Originally Posted by peety3


Quote Originally Posted by Jon Ruyle


And if you're worried about keeping ISO down in low light, the IS of the
17-55 will be a big bonus, especially at the long end.


Yes, IF your shutter speeds are in the range of 1/10th to 1/50th. If you're trying to stop-action with people, you need higher shutter speeds anyway.


Peety3, you initially recommended the 17-40mm f/4L. The 17-55mm f/2.8 is a stop faster, and has a wider range. Even so, it's not going to freeze people in dim environments. But, it's quite possible to shoot 'still' scenes with the 17-55mm handheld at night. I have a handheld shot with that lens with barely perceptible motion blur (can't see it on the 8x10" print, but it's there if I zoom to 100%) - I wanted to get nice water blur of a lit fountain at night, and the exposure was 1.6 seconds. That sort of shot would be impossible with either the 17-40mm f/4L or the 16-35mm f/2.8L.


Quote Originally Posted by peety3


if a 1D or a full-frame body is in your future, the 17-55 will be somewhat obsoleted at that point.


Only if the 1.6x crop is gotten rid of. When I get a FF body, I'll be keeping my crop body - and I'll want the 17-55mm to use one it. Also, the OP is talking about a forthcoming upgrade to the T2i/550D - a very nice body, to be sure. But, there are generally a lot of upgrade steps between a Rebel and FF. I would think a few years' use (through multiple 1.6x bodies) of a great lens like the 17-55mm will be more than enough to recoup the value from that lens.