You'll get differing opinions on that one. Could be fun to watch. Popcorn anyone?
I've seen plenty of 80% efficiency brews with the old hose plopped in the top. I've seen simple and innovative home solutions for sparge apparati. I've seen some pretty elegant and expensive SS sparge rings, that are damn tempting. Consider this - when Blichmann did the Auto-Soarge, they chose the hose on a float route. They do a lot of background on ideas before they release very expensive products. Some of which are a little odd, but anyway…
I've used almost entirely hose in the top, and haven't really compared this to using some sort of sparge apparatus. I don't think I'm experienced enough with both sorts to even have an informed opinion.
My guess would be your efficiency issue would be coming from elsewhere. What's at the bottom of that mash tun? How's the wort removed from the pot, and recirc'ed?