Federal Student Loans to Private

46K worth of federal student loans. I am seeing online offers for private lenders offering 3.39-3.47 interest rates.

1.) Collegeave.com allegedly offering 3.47 % 2.) Credible.com allegedly offering 3.39%

Has anyone had success with these other lenders? Our current federal rate is 5.5% (average). I’m looking to get our overall monthly payment down and I figure taking 2% off would make a good difference. Let me know if this is worth while or if I should keep everything federal.