I managed to finish up the class story line on the smuggler before the experience boost ended. Being part of a guild with a fully upgraded flagship is a huge bonus as well, so I managed to finish the class story line at level 60. I'm not even sure where to go from there, because I'm pretty sure that's the level to start KOTFE, just skipping Ilum, Hutt Cartel and Shadows of Revan all together.
I've now started on the Sith Marauder. I'm still not a big fan. I might try changing up his discipline to something else and seeing if that helps.
On my original main, Fiordin, I finished the KOTFE story line and have now started the first chapter or two of KOTET. So far it seems like more of the same. I'm anxious to get through the pieces that feel like you're just watching a movie, and hopefully the Onslaught stuff is back to more normal questing and progression. I'm guessing I'll be level 75 before even finishing KOTET (since I'm 70 now), but I guess we'll see.