The turn co-ordinator is a very poor instrument which is very hard to use for any sort of instrument flying. I was developed in the US when aircraft manuafacturers were doing their best to make their aircraft feel like automobiles of the time. The TC was an aid to making flying more smooth.
The turn and slip is far superior. All my training (military aircraft) was done using the T and S and the club I later instructed at had all the club aircraft refitted with them.
My usual GA mount is an aerobatic VFR only aircraft. A AI/AH will get damaged with constsnt aerobatiing so a T and S has been fitted as an emergency ''get you down'' aid.