Suggestions for a low-arch friendly cycling shoe, Sidi T1 unfortunately hurt!
Well I didn't know there was a community of low arch people, but I would definitely be a member of that group. My input may be of no help at all, but I thought I'd give my thoughts anyway. In high school I got achilles tendonitis several times during track season and the trainer recommended that I get orthodics, which helped tremendously. Because since I played soccer the place I went for my orthodics suggested I get a narrower pair to wear in my cleats (I ended up not doing that). I now where those in my Sidi T1's, and enjoy my T1's a great deal. I'm not suggesting that you get orthodics so that you can wear your T1's but if you've been having injury problems that's something you might look into, and then you could look into getting a narrower pair for you tri-shoes. I hope if this isn't helpful to you that it helps someone out in our wonderful low arched community.
I replaced the insoles with the Specialized ones in mine and have had no problems since. The do make the shoes have a bit tighter fit and I am lucky that mine were a tad on the big side before.
A cheaper alternative to orthotics is to have a physical therapist help you modify your shoes with layers of moleskin underneath the insole if they know what they are doing. Or you can do it youself wih some reading and experimentation if you have good body awareness. It looks like specialized came out with another new footbed that will do that if you know your numbers...
http://www.specialized.com/bc/SBCEqProduct.jsp?spid=12028 is what I have.
http://www.specialized.com/bc/SBCEqProduct.jsp?spid=13775 is the new one.
I tried and modified with a superfeet (blue) for low arches and had no cramps after an indoor training video. Thanks again for the suggestions, you saved me the hassle of selling used shoes! Those specialized will be what I replace the already-had superfeet with, they seem excellent.

Hope everyone had an excellent holiday season. I recently bougt a pair of Sidi T1 which fit my medium width foot perfectly in the store. To my dismay, I only noticed that the shoe was designed for med-high, high arches. This of course feels like a tennis ball under a flat-foot to low arch. I loved the shoes with that exception, so the question is to the low-arch community. Would you please suggest some medium width, low-arch friendly triathlon shoes?
Tribro, I am on my way to review the Sidi, and thanks for the site.