The IRS will balance out the car better. A little more weight in the rear will make a better balanced car. On bumpy roads, you car will no longer jump all over the place. Much more composed. The IRS has its place. I wouldn't mind having one on my car. Wheel hop isn't much of an issue in the apex.
I want to sell it?? I have had the car up on ebay, and all the classifieds in all the forums, cars.com/autotrader/racingjunk for over 150 days total...and every "serious" buyer I get backs out at the last minute
....so not to hijack this thread - an IRS will out handle a solid axle 99% of the time; however, an IRS will cost ALOT more to setup for a road race car (you need a diff cooler for sure, coilovers, full delrin/aluminum bushings, easily about $3000 in stuff right there alone). Also, with the cooling issues the IRS has (the diff center section is much smaller, and thus dissipates less heat than a solid axle) you will burn through diffs, bearings, and seals at a much faster rate than with a solid axle in an OT format. For a daily driver/street car an IRS is a million times better than a built/full suspension solid axle, IMO. The whole setup copes with bumps, potholes, dips, and imperfections in the road much better, while also inspiring confidence in normally adverse handling situations by balancing out the cars weight distrobution and by changing the inherent handling characteristics of the rear end of the car (waaaayy less "snap" happy, and you can keep the car from sliding going into the corner, and control the exit slide much more easily). I've had both (twice ) and like the IRS better, by far (Though I never put a torque arm on my solid setup, I did have c/o's, lcas, phb, and built internals).