I came from an Agency background and made the switch to doing freelance 3D and VFX work about 6 years ago.
Concerning hours, from my experience the work/life balance is just as demanding. It would depend if you are working on Ads, TV or Feature films.... but expect long hours and tight deadlines. 3D is can be substantially more complicated than 2D work and there are more technical considerations as well as things that can go south. Also, if you aren't working on Ads or TV, projects can last months. This is amazing on a good production but pretty painful on a long one. Teams are also typically much larger.
Salary right now seems way higher than working for an agency doing 2D or 3D. I would say somewhere around 20-30% higher depending on your skill level and professionalism.
As a side note, I would pick your software according to the field you want to get into. Specifically for VFX, C4D isn't used much. It's not that it isn't capable in many areas, it's just not a standard and will keep you out of other company pipelines which often means you won't get the gig. If you are on a small team or playing the one man band than that doesn't matter as much..... Anyway, lots of thoughts on this topic. I don't want to write a novel but feel free to DM if you want any other info or insights and good luck!!