The thing is, the the transforming and buffer output incurs its own loss, and as you go higher with the voltage, it may be more efficient to use normal cables. For instance, power leaving your four EV transformers will incur an additional power expenditure of 4*2^6 =256 EU for the four EV packages needed to make one IV package of 8192 EU total when leaving the transformers. If you use IV cables, you have an added expenditure of 2^7=128 EU per IV package of 8192 EU when leaving the IV battery buffer and you'll lose 1 EU per metre, so it's actually better to use the IV cable if the length of your power connection is less than 128 blocks.So 4 pairs of mfsu+gt transformer per 1 IV battery buffer. I could work with that, I'm sure I'll find a way to make it space-efficient
Which means that at any voltage above EV, battery transport in MFSU's becomes less efficient than GT cabling at short and medium distances.