I don't have a /550, but IME TiBooks aren't very fast. I had a 1GHz one and in actual usage at the time, with photoshop, it performed the same doing some heavy tasks in Photoshop CS2 as a Pismo/500 and a 1.83 Core1 MacBook Pro (with Rosetta, at the time.)
Some of that comes down to different things -- the pismo had a faster aftermarket disk installed, the TiBook was using the stock 60-gig 4200rpm (!!) disk and the Intel machine was 2x faster per thread than a 1.67 but PS was running in emulation and also it had, I think a 5400RPM hard disk.
In my experience, all Macs approximately G3/300 and faster feel about the same speed doing day-to-day puttering in OS 9, this includes using it in QEMU-PPC on my ~decade-old desktop PCs, where it benches close to a G3/300 for most things, although floating point suffers significantly.
Lots of that is just because OS 9 was really at the point where it's light enough that things can only really happen so instantaneously.
GeekBench is an OS X benchmark, one of the ideas I've had rattling around has been to build a MacBench database, but even then you have to consider some of the factors mentioned here like thermal paste. Anyway, I mention this because -- are you looking for a 9 or an X machine? If you're looking for an OS X machine, consider a newer PowerBook, or even an Intel MacBook Pro. You can run 10.6.8 on a 2011 MacBook Pro and the machine itself will probably last until the heat death of the universe and it'll be faster than The Quad at any PPC software it runs, although late era PPC software was usually universalbinary so it'll be
way faster than The Quad. Especially if you get a 15-inch quadcore model. There's also "all the other Intel Macs" and for the most part they're solid, stable systems.
Though, I realize that if you're looking for a specific aesthetic then suggesting a 2011 mac may as well be suggesting an M1 -- and, I do also suggest an M1 if you need a fast, productive computer.
I think that "too slow" may be (in this case) relative.
Agree completely. OS 9 on a TiBook/550 will be perfectly fine. OS X -- well, OS X on PPC was often characterized entirely by 2 year old machines feeling sluggish with new OS upgrades, even though they usually brought significant logistical and/or productivity benefits.
OS X will be tight on there but it'll probably be fine, especially if you can max the ram, the main thing the upgraded graphics gets you is better graphical smoothness and better performance at things that take time, since if you don't have a QE or CI graphics card, the CPU will be filling in. (You can disable some of the graphical effects to save time, I ran 10.4 on a blue-white G3/450 with a 16meg Rage128, and also on a Pismo/500 with a 16-meg Rage128, and it was fine on both.
Basically, I think that model Ti is the one to avoid.
As ever, inventory on all of this stuff is slim and so my advice is to get whatever you can.
The /550 may have been "the one to avoid" in 2007 when people were giving TiBooks away for free since they didn't really stand up to 2008-09's daily use very well, but most of us aren't using these things today like we're buying one used in 2007.
It depends on the scenario though. If someone doesn't have any portable macs and needs "literally anything" -- yeah get a Ti/550 if it's the first thing appears. If someone already has an iBook/500 or a Pismo or whatever, yeah. sure, hold out or pay more for "the one you want".