I have had no problems framing at 300mm using my inbody IS. I did
at first glance like the 30D with the IS lens because of the stable
viewfinder. But I have also run into people who get something
simluar to motion sickness with a stablized lens,because the eye
and the inner ear are out of sync. So it may not be universally
best... though I see some advantage at very long lenghts.
It all boils down to what kind of photography you do. For me, when I'm shooting birds, I can rarely get too telephoto. The 600mm + 1.4x TC + 1.6x body (
1400mm f/5.6 IS) was a perfect combination, but I'm sure if I could get more telephoto at the same quality, I would take it. I own the 300mm f/4L IS and 1.4x TC, which gives me a hand-holdable 672mm f/5.6 equivalent.
Since the most popular FF DSLR is a Canon 5D with a target market
that will also buy more espensive lenses. This is circular
reasoning.
Expensive is not always proportional to quality. My 100mm f/2.8 Macro lens is exceptionally good (sharpest lens I own). My 300mm f/4L IS is also good. My 28-135 IS is good enough that I don't know why Canon didn't put an "L" red ring on the front like they did with the 24-105mm f/4L IS. I'm not going to go out and buy a camera body just for IS. I bought my 10D in 2003, and I'm not spending another $1500 until the 5D or its successor comes out at that price (it will happen).
In lens IS is needed for Film.. though I have a film body I bought
recently to give me the choice.. I don't use it. The advantages of
digital with the current sensor quality trump most DSLR uses of
film.
I bought my film camera back when digital hadn't yet matured ($2K was the cheapest DSLR back in 2002).
2. DSLR users tend to keep lenses and change bodies rather than the
other way around. So even if Canikon upgraded the in-lens IS, the
user probably wouldn't.
Really? Have you done or are you referring to a study that actually
suggests this, or is this your "gut feeling"? What about SLR users
and DSLR users? IS has been around longer than DSLRs, and it works
on SLRs. Before you ask for "scientific proof", maybe you should
back up your claims.
Look at the price of 6 year old bodies vs 6 year old lenses its
pretty obvious. Even in the film days the Body features and
designs changed every 3 years or so, while some lense designs would
last a decade.. this alone would reduce the need to "upgrade"
Unless you think it is common for people to spend money for a new
version of what they already have that is working.
I did. I bought a 28-105 f/4-5.6 lens as my "kit lens" with my Elan 7. Then I "upgraded" to the 28-135 f/3.5-5.6 IS. I bought a 70-300mm Sigma for my Elan 7, and later I bought a 300mm f/4L IS and a 100mm f/2.8 USM Macro. I've rented and used a couple dozen different lenses. I've never felt the need to rent a different camera body. I know several people who changed lenses much more often than bodies. It doesn't matter that the lens designs stick around for longer. If I want a mid range zoom for Canon, I have several choices from Canon, Sigma, Tamron, and Tokina as well as using lenses for other mounts via some adapter.
Some people swear by the kit lenses, and some other people buy a "kit lens", discover its limitations and spend more money on a replacement.
My keeper rate is much higher for my IS lenses, particularly in low
light at telephoto focal lengths. For wider angles (15-30mm x1.6),
softness from camera shake at slower speeds just isn't an issue I
have a problem with.
those that assume IS with wider
lenses isn't useful, may just have not imagined the possiblities...
Don't mistake my words. Just because
I don't have a problem at wider angles doesn't mean that IS doesn't work there. Also, I rarely print my work or view it at unreasonably large sizes. I don't really have a hard time hand holding to get good 8"x10"+ prints. Perhaps it's because I'm still young and have relatively good hand-holding skills, or maybe it's because I'm good at composing so I don't need to crop too much. Maybe I'm just not terribly picky because since I went digital, I've felt a great jump in quality from my shots and I've learned so much from the instant review feature.
Still, if the 30D was available when I bought the 10D and the 17-55mm f/2.8 IS was available when I bought the Sigma 15-30mm, I would have bought them instead. All of my equipment works fine on my film camera and my digital. My intended upgrade path is to either a 1D series for its improved AF system or to the 5D (or newer model) for better sensitivity in low light.
If I could buy a DSLR with in-body IS that worked with my lenses, I probably would do so, depending on the cost and if the other features of the body were also improved. I'm not closed minded about these systems, and I've used quite a few other brand products and have quite a few friends who swear by X, Y, and Z product/technology. But I know what I know, and I talk from my experience
-Mike
http://demosaic.blogspot.com 
