The Sorane TA-1L has a highe effective mass than the standard SA-1.2. If you look to the picture of the SA-1.2, you see in the front the round hole. You can click in here an additional weight which will add 3g effective mass.
The Sorane TA-1L is a 12.7" arm, which will need 322mm mounting distance, which is a little more than FR66s.
Sorane is offereing an armbase with center nut fitting, similar to FR64s. Even the heavy nut from FR, the N-60 is fitting.
I prefer TA-1L with the more heavy arm base with center nut plus a heavy nut. Than adding a heavy Headshell, like 18g Yamamoto HS-5 will make the TA-1L fully compatible with the upper Koetsu carts, still not getting the performance of FR66s or Ikeda 407.
But as the arm is much cheaper, the performance is very fine for the price point.
Have not heard the Goovemaster in direct comparison,
but I would assume, that the difference in mounting distance (Groovemaster 290mm) drives most likely the decision