With gearbox oils one needs to get the basic parameters correct e.g fully synthetic (robust and long lasting) and GL4 (erring on the side of caution as mentioned above and not using GL5).
The rest is largely based on subjective taste and preference. Many people do not like a firmer “notchy” feel when cold but such oils will offer a smooth and less noisy operation when hot. Historically this is why ATF was used in some manual boxes although this might make them noisier when hot.
BMW manual gearbox oils have evolved in any event. MTF-LT-1 is obsolete and was thought to be mono viscosity 75W. MTF-LT- 2 was 75W-80. Both were GL4
If you put one in and don't like the feel when cold, you can change it again easily for say a thinner mono 75W and would have done no harm - in fact you would have done good by "flushing" the gearbox with a couple of quick succession oil changes.