bounce flash + image stabilization = ?

[Bo-Ming Tong]

I am tempted to buy a used Canon 28-135 IS and borrow a Canon but before 
I do so I wish to hear your opinions whether this is a stupid idea.

I have been doing bounce flash indoors a lot using a shoe-mounted flash. 
I started out with f/5.6 at 1/30 on ISO 800 film rated at 400 or 500, 
and got nicely illuminated pictures. Ambient light is only 1 or 2 stops 
below flash light. However, there was once I get blurred images. I 
wasn't sure whether it was my handshake or people moving, but it is not 
possible to handhold a 45mm lens at 1/30 and expect sharp results. So I 
switched to 1/60 last time. There was also not enough depth of field 
sometimes so I used f/8. My flash can still output that much power. My 
images came back not very satisfactorily. While the near objects are 
still nicely illuminated, the far objects are completely dark. I used to 
get at least some detail off the far objects.

As you can see, I am torn between a handholdable shutter speed, depth of 
field, and ambient lighting. Would an IS lens take the first one out, so 
that I can use an even slower shutter speed such as 1/15 and capture 
ambient light while keeping the aperture small for depth of field ? 
Obviously this can only help my hand shake but not people moving.

Or, should I "just do it" and use 1/15 since the far objects are out of 
focus and the near objects are mostly illuminated by flash at a speed of 
around 1/500 ? This might result in a sharp image with a blurry trail, 
though, if the flash light does not greatly outshine the ambient light, 
which seems to defeat the original purpose of capturing ambient light 
using a slow shutter speed.

Any comments ? I don't want to go Canon because of IS... I didn't 
realize there is any use for IS/VR until now.