There are some engineering "issues" with tangential decks that don't exist in a typical radial arm design. Firstly the tangential arm has to be driven by servo motor along a linear bearing to move across the record surface which means there needs to be a fairly complicated electronic circuit which "works out" where the arm is meant to be and then continually corrects/maintains that position. On a poorly set up or maintained system it can lead to treacking problems. On a radial deck none of this complexity exists - the stylus just follows the groove in the record! (with the disadvantage mentioned previously the the atitude of the stylus to the groove changes as the record is played).
That said, the majority of top class turntables of the day were radial designs - I think ulitmately their shortfalls are easier to design around than tangential decks.
The big advantage of a tangential deck was invariably "pose" value in that you could remotely control the arm position (not as good as it seems because, unless you are standing over it at the time anyway you won't be able to see where to lower it in the correct postion)
As mentioned elsewhere, the 5000 was thought to sound at least as good as (some thought better than) the 5005 etc.
Generally speaking, you aren't learning much if your lips are moving.