Staysails can be rigged to be self tacking with or without booms. the boom is cheaper and easier but in the event of an accidental tack or jibe while you are on the foredeck, the boom can take your legs out from underneath you. The boomless self tacking staysail is a little safer.
There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
Shakespeare, Julius Caesar IV, iii, 217