Running in FiveFingers, an Update

Since my last post I've run two more times in my FiveFingers and twice in my Nikes wearing Injinji toe socks. After a .86 of a mile sprint at an 8:30 minute-per-mile pace I developed a nagging dull pain at the base of the third toe on my left foot. The pain actually disappears when I put on my Nikes, but I can feel it when I walk around barefoot or in my FiveFingers. I don't know if you've ever felt this, but it's like when you need your toe to pop (crack your knuckle) and it just won't. That's what it's like.
Today the pain seemed to work itself out after about 4 miles and then I decided to sprint again - .85 miles at an 8:26 minute-per-mile pace - and there it was again. Weird.
So, I have all day to wrestle with whether or not to wear my FiveFingers in the Undy5000 tomorrow (5K race to raise awareness for Colon Cancer). I'm thinking it might be wise to wear the Nikes to avoid potential injury. I'll let you know.
I know many of you have been really interested in this barefoot running idea so I thought I'd keep you up to date.

RACE UPDATE: (11-22-09)
I ran the Undy5000 (5K) race in my Nike's with Injinji socks and set a personal record - 3.1 miles in 27:53 minutes (8:59 minutes per mile pace). I saw two barefoot runners at the race, these young ladies were shoeless and lovin' it.
I am beginning to think that this nagging pain on my left foot is actually just sore muscles. I am not used to having muscles in my feet so it's a weird feeling. I think with stretching and maybe icing it will get better. I am going to continue alternating runs in my Nike's and my FiveFingers until AFTER the 1/2 Marathon on 12-6. I will run that race in my Nike's and then put those on the shelf. From then on out I plan to train and race solely in my FiveFingers.