I have been asked whether the Cayo Adventure Tours shuttle service from the International to SI is reliable and to be recommended. And how reliably/punctually they leave. Someone has been assured by them that they can take their 3:30pm departure, even though their flight from the US is only due to land at 2:54pm.

Or would the services offered by William Hofna or others be preferable?

I think CAT is reliable but it is cutting it close to expect to make a 3:30 shuttle with a 2:54 arrival. But I guess if it's not very busy/flights not full/have only carry on luggage, they may make it. Or maybe CAT will wait if they are reserved & prepaid.