Closeup lens with kit lens: 250D or 550D ?

[sid]

I'm interested in Macro photography and currently have the Digital Rebel with just the kit lens. My interest right now is confined to static subjects. It appears that most people recommend the specialized macro lenses which seem to be on the expensive side (for obvious reasons). At this time, I dont have the budget to buy a dedicated macro lens and I was able to find a lot of good information here about the 250D/500D closeup lenses. So far I've read that:
(1) The Canon 250D/500D are optically superior to the 500
(2) The 250D is optimized for use with lenses from 50-135mm
(3) The 500D is optimized for use with lenses from 75-300mm

I've read posts recommending the 500D and using step up rings. (Also seen the excellent writeup on Roger Cavanagh's (http://www.rogercavanagh.com/helpinfo/18_500d-1.stm) website).
I dont plan on purchasing a lens that falls in the 75-300mm category any time soon.
So, my questions are:
(1) Is it worth it to get the 500D and steup up rings or just stick with the 250D ?
(2) More basic question: Which one (250D/500D) gives a better working distance ? (You can define "better" :D )

Appreciate the advice.

[Jon]

250D will focus at 25 cm, 500D will focus at 50 cm with the lens set at infinity. The 250D will give you a greater magnification with any given lens focal length. So you should make your decision based, not on the working distance, but on the magnifications you're going to want to work with (so, how big your subjects are). The closer the magnification gets to 1.0 in the table at the Roger Cavanagh site, the greater the magnification.

[sid]

Jon:
Thanks for the reply. After reading your post, I have a better understanding of the issues to consider. :)

[sid]

So, has anyone on this website used the 250D/500D with the kit lens ?