Jsut be careful of what color KSO you buy. The black ones are tighter than the grey/green ones for people with high insteps. So get the grey/green KSOs and you should be fine.
I had the same problem. I have high, wide feet. I ordered 2 pairs of black KSO's, 41's per VFF website, and 42's. Neither fit me. The 42's were close, but the strap only overlapped the velcro by about 1" (2-3cm) and the fabric across the top was very stretched. I plan to try a Grey pair if I can find some locally.
Ok - so I think I've figured this thing out (famous last words).
This morning, I took a good look at my black KSOs and grey KSOs to see if I could spot any differences.
Lo and behold I spotted a difference at the distance from the curving mesh fabrick to the sole and the thicker/hard fabric strap mechanism.
What you want to do is look at the Vibram "stamp" on the thick fabric and then find the stitch that runs above it. Follow that stitch out to where it T's up with a perpendicular-ish stitch. Then, look to see how much non-mesh fabric is between where the thick fabric ends and the mesh fabric begins. With my black KSOs, there is basically zero of this fabric. For my grey/green KSOs, there is a good 7/16 of an inch of fabric between mesh and hard fabric. These are M43s, Now, it'd be hardly scientific to extrapolate from my case to all cases, SO if you have a pair of KSOs, take a side photo and measure this distance. Upload the photo to imageshack.us (free, simple, no registration) and then post the photo here. All colors would be helpful -- even (or especially) others with black or grey KSOs.
Let's see if we can get specific on this!
I noticed that the peice that says "Vibram" on it is bigger also. If that's the case, the grey ones should fit me better. If this is indeed a QC issue (different fit for the same size shoes) I may stay away from them all together. I've already dished out about $15.00 in return fees. The folks who have free shipping/returns are usually more expensive so it's a wash.... pay more for free S&R, or pay less and hope they fit.
My black 42's fit well enough. I'd like to get a pair of Grey/Green ones for less than formal occasions. I'll try the GG's in 41.
**Update** After wearing my 42 KSO's around the house a little, I've become concerned about the tighness of the mesh and fabric on the top of my feet and the amount of extra hook velcro on the side. My wife even noticed and said that it looked like they were ready to explode (I don't have fat, meaty feet, just wide with a tall instep). I think they will be going back also. I'll try the GG's later, but for now, it's back to nekkid feet.
On a secondary note: I'm also not to fond of the cut of the sole for the pinkie toe. My pinkie likes to hang out a little so the sole doesn't quite cover the entire bottom of my toe. The sole is cut to let your toes crowd together like they are in shoes. Since I don't wear shoes much, and when I do they are sized pretty wide, so my toes are spread a little more naturally (much to my wifes chagrin).
My black size 42 KSO's are going back... they look/feel as if they are about to pop with my FF's (flintstone feet). If I find a pair of grey's I may try them again. Until then, it's back to nekkid feet.
I have wide, tall "Flintstone" like feet. Vibe's site says I should wear a size 41 KSO's on my perfectly matched 10 1/2" long feet. I bought 41's and felt like they were just about to tear stretching them over my instep. Once on, the strap only overlapped the velcro about 1" (tall feet remember) and my toes were squished. Even though I was worried that the 42's might be too big, I ordered a pair anyway. The 42's fit much better. I can overlap much more of the strap, I don't feel like I'm destroying them just putting them on, and my piggies are happy, all in their pockets with a nice hug (no squishing). I guess Vibe's recommended sizing is for "normal" feet. High instep "Flinstone" foot types may want to size up 1.
BTW, mine are black, since my feet look like gorilla feet anyway...
I have much the same problem with my new black KSO's. I measured (about 40+ times) and ordered per the chart on their site. I can barely get them on my tall feet. Once on, the strap is almost extended to the point that it won't hold. My didgets are a little folded up too. I ordered the next size up to see if they fit better. If they do, the smaller ones are going back (at my expense). At the very least, I'll know what size KSOs I wear.
I loath shoes. I have "Flintstone" feet (short, wide, with a tall instep). I love my feet. Not others feet, I'm not a foot fetishist...or fetisher... or whatever you call someone obsessed with others feet, just mine. My feet are happiest when they are free and bare for all to see... some stare.... they must love others feet... or just mine. My feet like the snow. But not too much, just a little. My feet like to be touched, not by others, they think that's a little creepy, just by me. I like to touch my feet (is that creepy?). My feet like rocky stream bottoms but they sometimes get the Jeebies when they touch someting that moves. I love my feet.
P.S. My feet like their new VFF KSO's. They want to wear them to bed... I said no, It's a school night.