Contract Work

So I guess I can preface this by saying that I'm being recruited by an agency, and the work that I do is fairly specialized and in high demand. I get a legitimate recruitment call every month or so.

So this latest offer is for a contract to hire position after 6 months. Yada yada yada, implied promised that all his recruits get hired, etc. I'm not buying it fully, so there is still the risk of the temp position. This position would be straight hourly for 6 months. So any day off would mean no income.

Anyhow, this is what I've figured for compensation. Also, I'm assuming 261 potential work days this year. (# of M-F days). I know you can't count income like this when you're not working, but considering an hourly wage, I find it necessary to compare the total package.

Current:
Salary: 85k
PTO + Vacation + Personal Days= 31 days.
Adjusted salary: $98,163.72 (salary * (number of working days / 261))
401k match: $5,100
Company paid portion of benefits: $12,216.00
Current total compensation: $115,479.72

Potential: (all figures per year)
PTO + Vacation + Personal = 18 (time off would get expensive, so I cut it to 10, 6, 2 days each)
401k and benefits would be $0.

The break even point is: $59.40/hr (at 1944 hours worked per year). This is in the ballpark of what they're starting at offering, so I could negotiate that up a bit, but that is the break even, and does not assume the risk of it being a contract position. I would be working for an agency as a contract employee, rather than freelancing, so I wouldn't incur the extra tax burden. That said, a lot of people in my profession only do contract work. Also, my wife is employed, so we could take on her benefits.

Am I missing anything, what are your thoughts, have any of you ever done contract work like this? Thanks in advance.