My Athlete Live?

Yes, I have used it, for 3 different IM's.  The ordering/shipping process is super easy.  You can rent it for one day for an IM, they will ship it directly to your hotel and everything is included for the return shipping.

It worked great for IMFL, so-so for IMLOU and not well at all for IMLP.  It does require cell service, so I'm not too surprised that it didn't work so well in LP (mountain area).

My out of town friends/family say its easy to follow from home (when it works).

I've used it 2x.  Worked great in IMFL and not so much for IMLP.  Both times we rented the tracker for a week.  It worked great the first time but the second time the tracker was never "cleared" by the company.  It had me in Des Moines.  I emailed frantically w/ them in the few days leading up to IMLP and they kept saying it would work, it would work, not to worry.  It didn't work. I was still in Des Moines.  They were very apologetic, said they'd refund my $ and next race is on them.   The little tracker thing does need to be placed pretty carefully in the plastic casing so it doesn't fall out. 

I used it at IM Louisville last year and according to my family it worked great. They seemed to get the most results out of tracking from an iPad but the smart phones also worked (wouldn't attempt from a Blackberry or non-smart-phone).

Shipped directly to my hotel - it was waiting for me at check-in.

I used it at Wisconsin two years ago.  My wife couldn't track me from her iphone.  It worked fine on her phone the day before the race, but for some reason did not during the race (very well could have been user error on that).  But friends on the computer had no problem with it.  It really helped the wife out having friends tell her I was at mile whatever. 

The device itself was pretty small and light, about the size of a small pager.  I didn't notice it at all during the bike.  On the run, every couple of miles it would work itself in to the middle of my back and I'd start to feel it bouncing.  But I couldn't feel it when it was pulled over on my hip.