I have a couple sets of TI flats for my Super J 5, B-G and E-C. TI flats are my all time favorite. The TI's fit the five string Super series, but require some fiddling with setup, namely some shorter saddle screws, since the whopping .136 B string, and the E strings are not tapered at the ball end.
Before I cut up a set of TI's for E-C, I wanted to test out the E-C idea with a less expensive set of strings. On a whim I bought a set of DR Pure Blues, 105-45, with a 30 C string. The outer wrap and feel is very similar to DR's nickel low riders, but the tension is lower and the feel is softer and slinkier. I ended up with the lowest set up ever and I'm really happy with the strings. I even ground the saddle screws off shorter to test the limit of low. With the DR pure blues the neck relaxed to almost dead flat.
I just bought a 100-40 set with the same 30 C string, can't wait to set these up. I might be pushing the limit on the nut, but we'll see. I really like these strings. I'm back on a nickel round wound kick.
Previously, on the Super J ive used: nickel lowriders, Hellborgs ( with a Dingwall B), Dingwall nickels, sunbeams, and the TI's. You get lots of string choices with the Super series.