I have a big question for tokamak devices and similar: how heavy are they for a given power, including boiler and ancillary equipment? When discussing space related fusion this is a key parameter. I get the feeling that it's incredibly heavy for the power output.
Excellent question. Ultimately, it's just a heat source, so the same considerations apply as to fission reactors in terms of turbines/generators and radiator mass.
(aside: is the output temperature as high as a fission reactor? that will affect efficiency)
If we're talking about propulsion, then direct drive concepts like *ahem* Direct Fusion Drive or that lithium liner concept (the name of which escapes me) will have the edge - if they ever get them to work.