Ideally someone could do a comparison in the 10.8V range.
The Metabo PowerMaxx BS and the Mafell A10M I believe differ in:
1) Systainer versus Metabo box
2) No bit holder with the Metabo (??)
I got three of the bit holders:

The Cnetrotec bits fit well enough and all the 1/4"gear fits like a champ.
The green-lipped Centrotech bit holder also fits.
I have no idea about whether the Wira holder fits... ??
I got a used Festool offset chuck but it was slightly too small to fit so I donated to my Festool-tragic friend.
I like it with the small battery for general work.