I'm a friend/T Supv. in a dep't outside of Ops, but I started in Ops and promoted through Ops.
You will be disrespected by Union members and mowed over by upper management, but it's not a bad way to go. I graduated from college debt free. Not too many people can say that, in a world where McDonald's employees think they deserve $15/hr. UPS reimbursed me for about 50% of my college education costs (I went to State U). If you decide to go for your Master's degree, UPS only pays for $150 per credit.
Benefits will cost you about $650/yr out of paycheck (after incentives) for the high deductible plan for you plus family (includes wife and ALL kids). This includes medical, dental, and vision. Your deductible will be $3,000/yr and your total out of pocket MAX will be another $3,000/yr (TOTAL = $6,000/yr). You get to contribute to an HSA (like a piggy bank for medical, dental, vision, chiropractic, etc.), and I recommend that you do. The low deductible plan will cost you about $4,500/yr out of paycheck for the same coverage, and your deductible will be $250/yr per individual or $500/yr for the household. Your out of pocket MAX will be a total of $2,000/yr per individual or $4,000 for the household.
The pay sucks, which is to say it is inadequate and varies wildly. In the same way that drivers who join mgmt. start off with a much higher salary than the poor schmuck like me who has worked his way up, customer counter clerks will also come in making the MAX, typically, so be sure to ask for more. Treat this like they need you more than you need them, but be respectful. The reality is that you literally have nothing to lose by asking for more, hey what's the worst they can say? No? If that happens, you have two choices: accept their offer or stay in the Union ranks. Either way, you have nothing to lose.
You will be paid a salary for 27.5/hrs per week, and you'll have to fill out a week and enter your hours daily. if you work more than 27.5hrs/wk, then you'll be compensated for the additional hours on some sort of prorated schedule. If you work more than 40hs/wk, then you'll get overtime (1.5x).
Even if you choose to promote to P/T Supv., there's still a chance that you could become UPS pkg. driver. Depending upon opportunities in your local area and the political climate internally there, it may even be a way for you to fast track your way to becoming a UPS pkg. driver. Honestly, if I had the opportunity to become a UPS driver tomorrow, I'd take it in a heartbeat.
The choice is yours to make, my friend. Good luck!