I don't get what the big scare is about the aluminum rims? Check some of the you tubes the down hill stunts and all the curb tricks for bunny hops etc. Thats what they swear by according to those forums and I as well! Mag wheels among stunt riders are said to be the weakest they crack! Many steel rims come with the worst axles . I would take a high end free wheel cassette hub with aluminum rims over steel any day. You won't find that on a walmart bike. Front rim and hub will usually always be fine.
If you weigh as much as a horse jockey you can use anything. I made a a low end walmart hub work fine until the spokes broke 4000 miles. It was aluminum and ran on the Jshaft just fine. Because it was a cheap hub the axle would flex and need to be properly set for bearing end play a pain for some folks! A high end aluminum hub you set the end play on the bearings once. I even drill a hole in the center for a grease cert.
My currant build has a jshaft Bike and I are 300 plus pounds! One any given day I will be carrying groceries etc. Because I did not mount the front part of the china right the rear gave me a little hassle but that wasn't the kits fault! I simply adapted for it. Once I ran the bugs out? Oh man I would not run things any other way this thing has really spoiled me!
Check this link out if you doubt aluminum rims are any good! Aluminum is stiff it can flex and even move back. Steel don't flex and bends easily. Pound for pound the aluminum is better! I am sure some steel versions have better hubs I am just not interested in them.