Dayton RS180 vs Dayton 6.5"

For those of you who have actually heard both. Which one would you recommend in a 3 way to cover from about 60hz - 300hz. Would the RS180 sound significantly better? Would it be worth buying the RS180s when I already have the 6.5s".

The speaker I'm building is going to be a 3way used with a sub also. So really it will be more like a 4 way. I had planned to use a MDT33, Peerless HDS 5.25 for mids, and then two 6.5s for bass. This will Eventually be combined with a Sub. But the DOTD has me really tempted to replace the Dayton 6.5s. What do you suggest???

Thx!