IMO, a patent agent only makes sense as patent law bootcamp and a resume builder for a patent atty job. Maybe working part-time during law school.
You have two major patent-based jobs that are opposite sides of the coin: patent atty vs patent examiner. There have been many discussions, some my own, of the relative benefits of both. Assuming a sharp person who could excel at either job, it comes down to Work/Life/Flexiblity vs. Pure $$$.
To me, an agent doesn't fully reap the benefit of either.
The straight dope on average base salaries (as far as Glassdoor is concerned) is Patent Atty: $143k, Primary Examiner: $122k, and Patent Agt: $103k.
Now this is base salary, and the bonus for patent attys is usually significant, but I'd guess the average non-partner pulls down $160-200k a year, working 8-10 straight hours as noted above. A lot of the allure for the atty route is the golden pot of honey called "partner", but it's a giant pyramid scheme and also relies on some luck.
Primaries make more too through overtime. This really just translates into more quality cases preformed. Its a lot like inellectual piecework. As a primary and some OT a week, $160k can be had without the gruelling constant work above. Flexibility and Autonomy are unparalleled for a Primary, but you'll never be "ballin'" with the cash ceiling. Work from home sealed the deal for me. I had been 99% sure I was headed to Law School after a couple of years of experience.
Now a Patent Agent has none of the flexibility, work/life, or lower stress of the Primary. At the same time, while I'm sure it's possible to bust your ass at a large firm and maybe make 200k, it would be disheartening to know you could have made 50% more with the same effort (that's just throwing out a guess). I would guess that a significant majority of Primaries out-earn Agents. The important thing to note is it would take about 5 years to become Primary (assuming you're a good examiner).
After 15 years, the questions I would ask is how much do you work, how much do you get paid, how is your work/life, are you stressed? I strongly believe the ONLY benefit of becoming an agent over an examiner is that you would probably be paid more the starting few years. I can't think of another benefit.
I've also found "pure engineers" to not always pick up what it takes to be an efficient quality examiner. Being an efficient quality Atty is even more difficult. This is something to consider as well as far as staying put.
My experienced is based on 10 yrs at the PTO, knowing several examiners as well as examiners-gone-private, and chatting with current attys during interviews. Currently have a friend who went private and came back.
One disclaimer about my adoration for the Primary position is that I work in the mechanical arts. I can't really speak for EE. That being said EEs are very in demand. I think with a masters they could offer you a GS-9. With one half-year accelerated promotion, you could be a GS-12 and work from home in 1.5-2 years. Assumes ass kicking at the job. Experiences vary.