I am all Per-diem.
As far as benefits: do the math, on paper, and compare apples to apples.
Full time: First figure out how many days a year you really have to work. If your shift is 3 12's for example. Add up all your sick/vacation/personal days. in my case, that's a total of 5 weeks a year, meaning I have to work 47 weeks a year. Whether I take, or accrue, all this time is irrelevant- averaged out, I have to show up 47 weeks, and get paid for 52.
Using round numbers, if I get paid $20 an hour, I get paid $37440 a year, plus insurance. If there are any retirement benfits, fix a dollar value to them, and add that as well.
Assuming I only work the required 47 weeks at time and a half (that is what some per diems pay), i will earn $50,760. If I want to "accrue" time, I'll work more than 47 weeks a year, just as if I was salaried.
This gives me over $13,000 a year to make up for insurance and any other "benefits" the hospital might give.
Depending on the finances, per-diem can work out well. Job security is another issue. You may need to find several per-diems to keep busy. You will also have fluctuations in pay. If your life is based on borrowing money, then making monthly payments, per-diem might be nerve wracking.
Works out fine for me.