A caged pulled retains the factory style pulley support. On a mild truck with say a 4lb or 6lb pulley they're overkill.

A simple hub and ring or solid pulley will work fine.

 

Exactly what JDM used on my 04' been on 7-8yrs never a issue.

 

The caged pully has a bearing support to transfer in-plane loads from the blower belt into block, minimizing loads on front of crank. Only rotational loads go through front of crank. (I've been told). Aftermarket pully bolts directly to crank damper.

I have run a direct bolt on crank pully for 120,000 miles with no problems, but then I don't drag race.

 

The caged pulley to meant to prevent this. (Not my picture, but one I found with a quick search)

This can happen to a Lightning, but was way more prevalent with a Terminator. Still a Terminator uses 1 belt to drive the blower, and all the accessories. The Lightning has a dedicated belt just for the blower. This was mainly an issue for people trying to combat belt slip with a very tight belt setup which put a lot of strain on the snout of the crank. The brace just absorbs the load the belt puts on the crank snout. Is it needed for most applications? Probably not. It costs more, is heavier, and is more aggravating to change the inner accessary belt when the pulley is braced. Still some thought they didn’t need a brace, and it bit them. Again it can happen on an unbraced Lightning crank, but was more common on Terminators. In fact it was a very known issue in the Cobra community. I will point out the Ford/SVT determined that both the Cobra and Lightning needed a brace on the OE pulley, and a stock pulley isn’t under as much tension as most aftermarket lower setups running extra auxiliary idlers and whatnot. Belt slip isn’t a big issue at slower blower speeds.

I don’t have a recommendation either way. Both routes have their logic behind them, but it’s good to understand the reasons both exits, and the potential risks regardless of probability.