polycarb jigs are far more accurate than anyone requires and easily as accurate as a bitz, will take incredible abuse, have an indefinite lifespan.
i've had a martin j8 polycarb fletcher that's at least 20 years old, probably more, have fletched many Many hundreds of arrows with it for both 3 and 4 fletch, it's as good as new in both looks and function. now, it's my dedicated 75x105 offset 4-fletch jig.
for helical i have 2 bohning polycarbs, one setup for 3x120 offset and the other for 3x120 helical.
just got a new grayling polycarb for $32 @ braveheart - what an amazing, precision quality fletching jig that will do 3x120 and 4x90, for solid performance/quality value. this is now dedicated as my 4x90 helical 4-fletch jig. this jig even comes with an added rotating idler shaft arm that's multi-notched to handle both skinny carbons and fat woodies. imho, this is the best quality, performing, priced, and overall valued fletching jig available anywhere.
nothing at all wrong about a bitz. they were the first commercial cast metal fletcher (instead of bent/riveted metal like on the hoyts and jans) and before the age of solid hi-performance plastics. ymmv.