From what I remember of the Rabco arm is that it was worse then a normal pivoting arm, when it came to tracking error. The mechanism simply had to much "slop" before the arm made corrections.
In principal, the tangential arm is ideal. In practical terms, unless you can afford the Clear Audio arm at about 10K, it's not worth even a second look.
Now that these arms/decks have aged even further, I only suspect the problems have become worse with it's error correction.
My advice is to pass and give up the linear tracking tonearm quest. There are alignment problems with these, too, so your quest does have some problems.
Just calling it as I see it. Hate to be brutal, but.....