Considering paracorr for f5.6?

I am considering the purchase of a 1.25" paracorr for a 10" dob f5.6. Does anyone have experience with a paracorr in an f5.6? Also, are the TV paracorr's compatible with other brands (e.g. Pentax) of eyepieces? What about barlows?

Thanks for input.

1. Hard to find...1.25" no longer made.
2. At f/5.6 you may not need one, esp with 1.25" EPs.
3. Yes.
4. Probably not needed with a barlow.
Bill