Because aluminum doesn't flex and it is a white metal, it is brittle and tends to snap. It takes the impact and usually just transfers that energy to the next part, to the next, so on and so on until it finds a weaker part and breaks that. In the case of the arms for example, it would transfer to the bulkhead. Because they have more parts attached to them, they are usually more labor intensive to replace and can tend to be more expensive as well. This is a general statement, not saying that this is even how your particular rig is built... Just explaining the theory behind my statement. Rpm is nice because their parts are more flexible than the stock an are better built (imo). They also carry a lifetime guarantee. So that's my thoughts on the aluminum. Certainly there are applications where they can be used and serve their purposes well. As far as appearances go, your rig speaks for itself! You SHOULD be proud! It looks GREAT!!! I am Def looking forward to seeing your basher go! Post vids if you can! Def do a write up with pics of the build itself! It will be helpful to lots of ppl, lots of ppl have the tmaxx! I'd love to see the maxx running a .32 tlr!