I think your rod is a bigger problem than your reel is. I would imagine the moderate action of the rod is what's hampering your casting distance with those light inline spinners. If you have any other UL rods with a fast or extra-fast action try tossing the spinner on that before you write off that reel.
Just for some info, I have a UL setup that is dedicated to throwing inline spinners. The majority of the time it's 1/16 oz Rooster Tails but sometimes I bump up to 1/8 and branch off to Blue Fox, Panther Martin and Mepps. I've never had an issue with the blade spinning and i'm usually slow rolling them. Setup is a St. Croix Avid 6' UL/Fast and a Shimano Stradic 1000FJ. 6 lb. Sunline Super Natural to a size 10 Spro power swivel to around 15" of 4 lb. Sunline Super FC Sniper. The Stradic is 6.0:1, not sure about the IPT.