Siemens has recently changed their design somewhat for the better I think.Their latest design has a field installed grounding lug terminal seperate from the neutral terminals.This aids in both main lug and main breaker apps.Although you need to be careful with the load center covers now.I think they have changed the can to one size ,so a 30 cir. and 40 cir .can is the same with the interior size of spaces being different.The older version of Siemens with the copper bonding strap ,I always land my neutral on the neutral side and the grounding conductors on the other side.I have seen the copper strap loose from the factory ,even though the screws checked tight.There have been times I have seen the screws cross threaded.I discovered this loose strap problem on a service call.And we all know what effect a loose connection has on electronic as well as other equipment.