Well I dont'n know if the'yre better or not. Several websites have reported that new mahle piston sets are actually cast and not forged (for example, cip1.com and aircooled.net, under hte product description). However, Mahle is doubtless a very high quality brand when it comes to aircooled pistons.
According to cip1, the AA are true forged, however they're made in China
Here you can see for yourselves:
http://www2.cip1.com/ProductDetails....C%2DC10%2D5167
http://www.aircooled.net/new-bin/vie...18200773348335
http://www2.cip1.com/ProductDetails....C%2DC10%2D5204
Note that AA are about 50 bucks cheaper. You can blame that on branding, or on quality...
I really don't know about type 4 cylinder walls, but why don't you make a search on the forums on thesamba? You might find very good T4 combos in there.