I used a similar guide -- can't find it now but this one looks easier to follow, especially the maps -- to unlock the FSD booster.
Doing the puzzle and material collection took roughly the same amount of time as one of the World Cup games that I was watching on the second screen (don't ask me which game; all I remember is that it didn't go to extra time) then a bit longer to get to the tech broker and unlock the module. So a couple of hours in total. It was worth it to get the insane jump range on my exploration Anaconda but I'm not sure I could be bothered going through a similar process for any of the other Guardian modules. I might feel different if I engaged in anti-xeno operations.
One tip: once you've solved the puzzle and got the Guardian blueprint and are just gathering materials, finding the last couple of shootable towers or ground structures can be tricky (although to be fair these clearer maps might help). If you're struggling, re-logging to reset the instance puts all of the other material towers back into play and makes it trivial to find the materials, although obviously this also re-spawns all of the sentries.
I'm not convinced by the necessity of an FSD booster for general purpose ships, but for long-range exploration it's a must have. But once unlocked you can buy as many of them as you want, so there's no harm in experimentation.
I quite fancy fitting one to my already nuts-range bubble-taxi DBX but that's on my other account, which means doing the puzzle again. When's the next televised international football game?