I'm no expert, but my understanding is that "around half a second," relates to bib-mounted tags. if the tags are attached to the shoe the distance from the tag to the antennae is reduced and accuracy increases. I will also be using it mostly for timing middle distance interval sessions so 200m, 400m, and so on up to around 1200m rather than sprints (I have a young lady who times the sprints for me).
I looked at Freelap.
each of their tags costs £186 pounds. with timing mats I can get tags for 12 pence each. that's a ratio of 1550:1 which is, as they say these days, a no-brainer.
I'm not particularly interested in super-accurate timing. I have two main priorities:
1. releasing me from the task of being a data collector so that I can concentrate on being a coach.
2. super-accurate is not important, but consistency is. I want to be able to compare the times a lad runs today with what he ran three weeks ago, and if there is an error I want the error to be consistent from one session to the next so that his times can be compared with each other. I want to compare his first rep with his last to see how well he started the session, controlled his effort, held it together and so forth, but I'm not interested in comparing him with some other lad or my lads with boys from another training group or with what Jim Ryun ran in 1969.
and, suggestions from several posters that lads wear watches and time themselves are obviously coming from folks who have not actually tried this. modern youngsters do not wear watches, that's what their phone is for. in my training group there are only 3/4 lads who even own a watch. you might as well ask them to wear a wig.
cheers.