Doesn't really matter, they're in the same class of machines. This feature is intentional on Alblaka's part. He's the creator of IC2, which contains all the machines you're using, and he has dictated that losses are part of moving machines, so it's unlikely to change soon. You can resolve it in one of three ways:
1) Suck it up and lose some machine parts in rebuild every once in a while.
2) NEI the machines back in and throw away the machine blocks when this happens. Cheat, in other words.
3) Use an Electric Wrench with lossless mode (hold M and right-click to switch) on. This consumes a lot more power, so a batpack or lappack is advised.