phk writes ...

I've been reluctant to switch to DSLR because of the potential problems
with dirty sensors caused by the ability to remove the lens.

I would call it a nuisance but definitely not a reason to avoid
switching to a dSLR ... I usually don't see it and when I do see it it
typically takes 30 seconds or so to clone the specs out of the image in
Photoshop.

Is this a real problem with DSLRs, or not as bad as it seems

The smaller sensor models (1.5x, 1.6x) don't show as many problems, I
found I had to clean a 10D every 3 - 5 months for example (1.6x). The
larger sensor models seem to attract more dust and require more
frequent cleaning though. My 1Ds needs it typically once a week,
sometimes more often if in a dusty environment.

You only see the dust specs at small apertures, btw.

It appears that Canon recommends use of a hand-held blower for
dust removal, but I wonder whether that actually works.

I've used the Giotto Rocket Blower that Bob recommends in another post
to this thread and it didn't get all the dust off for me. I've used
the Sensor Brush and this usually gets everything off unless there's a
smear. If there's a smear I use a Pec Pad with Eclipse fluid, but this
is rare. After a while you get used to doing it and it's no more scary
than cleaning the front of your lens.

The Oly 4/3 bodies have a better way of cleaning the dust, done when
you turn the camera on, but there are a couple of other long-term
issues with this system that keep sales low and would keep me from
buying into the system. But if you're really paranoid about dust this
may be the best system for you.

Bill