"Is this (Lee Challenger Breach lock press) worth it?"
Certainly so, or Lee wouldn't be selling thousands of them each year. I've been reloading for a long time and have six presses from four makers and they all work fine. I have no blind brand loyalty or animosity to inanimage objects, I choose tools strickly by the uses I will put each one to. That said, all of the cartridges you list are easy to work with except, possibly, FL sizing the .300 mag. and, even with it, proper case lubing will allow you to do anything you need done. However, I find Lee (and Hornady) 'quick change' die systems to be pointless and costly for no real purpose.
There is NO reason to use wrenches or pliers to install dies; hand tight is plenty and that's why so many dies come with knurled lock rings rather than hex rings. I can swap screwed in dies in about 35-45 seconds, so it takes me about a minute to a minute and a half to change two-three dies for a full session. Even if those bushings were instantaneous swaps that wouldn't "save" enough time to improve my life style in a normal hour or two of reloading! ??
All our makers produce excellant reloading tools but it's wise to make purchases based on the way you will need to use things but if I suggested you buy my choices you wiould be buying for me and our needs may be radically different. And some of what I use would be different if I started over next week anyway, especially my presses! A beginner's needs are no less stringent than an old hands but they are often quite different. Old hands tend to be into a bit more than basic ammo production. I mean, IF you plan to load modest quanities with conventional components that press will do you for a lifetime but IF you plan to do widlcates with major case reforming you will need an all iron/steel press instead. Or, IF you plan to load hundreds of rounds of one kind all in one sitting you will need a progressive press or at least an auto-indexing turret press. Etc.
My suggestion to anyone loading modest quanities of your cartridges, especially the big magnum, is to consider Lee's Cllassic Cast single stage press; it's all iron/steel and really doesn't cost a lot more than the Challenger press. The CC is very large, very strong, has a larger diameter ram (longer wearing) than others, the lever is fully adjustable for side/length/angle, it's precisely machined on computer controlled tooling and the spent primer catcher actually works! IF the CC had been available when I bought my Rock Chucker that's what I would have now, it's really a better press than my RC.
Good luck, and enjoy!