I built a Coho last winter. Nice boat, pretty & handles well. It is a high volume boat that seems well suited to either a large paddler or for someone who needs a high capacity boat.

On the building side, remember that the coho has an eight panel hull, with three pieces per panel. Another four panels on deck, each with three pieces. That means 36 butt joints & lots of wire ties when it goes together. The experience you gain working with the epoxy and glass tape on the butt joints does pay off when it the time comes to glass the hull and deck, however.
I wonder if the simpler Tern hull would go together much faster. Near as I can figure, the tern has a 24 piece hull which makes for a slightly more controllable project (1/3rd fewer joints). Any extra time saved could be used to put on another layer of varnish when you get the boat done.

You won't make a mistake either way - these are fun projects that are easier to complete than you think.