Ive used borrani alloy rims for years, they are very strong, if you are able to break one mounting a new tyre then you should review your mechanical sympathy settings. Rim protectors will prevent damage when mounting new rubber. Strong enough to remain round in an impact that will bend fork stanchions.
Although there is not much of a static weight saving , the weight saved is at the outside of the wheel diameter, any weight saved here has a huge effect in reducing wheel inertia, this improves acceleration , braking , flick-ability, and unsprung weight.. They look cool IMO, and dont rust.
Alloy rims improve braking, acceleration , suspension and handling.
The only downsides to flanged alloy rims is that they are a barsteward to clean. Changing rubber is marginally more difficult. neither of these downsides would make me use steel rims.