Although the world record for DX on the highest microwave band (241GHz) allocated to radio amateurs is measured in several tens of km, the UK record is quite modest.
My own view is 481THz optical is much easier: test gear is trivial and all the gear can be made inexpensively by nearly anyone. Microwave gear is much harder. I know people say you can "do microwaves" with minimum test gear, but I think you will find most who are successful are, or were, in the business professionally and have access to good microwave test gear. With optical gear this is definitely not the case. Before my stroke I built all my optical gear in the back of a garage and I achieved very useful results. Others have achieved far more than me. All you need are a scope, a multimeter and an audio generator. Much of the test gear needed for optical work is freely available software on the internet.
See http://www.microwavers.org/?241ghz.htm .