Aluminum Flywheel Vs Steel

Has anyone had experience with steel vs aluminum flywheels? I just upgraded my 2011 motor (ford racing 5L) and had a new spec clutch installed. Just got it yesterday from the shop. I noticed a lot of clutch chatter in first, and in 4th gear at about 1300 rpm, the vibration noise is for lack of a better word, undesirable upon acceleration. My stock single disc clutch had a steel flywheel and never had this issue. Since I'm new to this clutch, thought I'd see if anyone had a similar issue. I'm about ready to take the spec dual disc clutch back out and put my old stock back in. Any thoughts?

Yes. That probably is part of the problem. First I bought an dual-disc RPS clutch with a steel flywheel, but when it arrived it didn't fit. The mechanic them ordered a dual-disc clutch from SPEC; unknown to me it shipped with an aluminum flywheel. After the mechanic installed it, I looked at the assembly and found that it too didn't fit well, as the bolts to the clutch were sticking out so as to prevent the cover from fitting properly. He had put washers on so the cover plate could be attached. Anyway, I drove it and have a vibration and like a buzzing noise which occurs under load - specifically in 3rd thru 5 the gear all around the 1,200 to 1,600 rpm range. I thought it might have been the plate, not being attached well, was vibrating, but another person said the flywheel may not have been balanced. Since it is aluminum (which I have had no previous experience with and didn't know till after it was installed it was put in) when I push the clutch in after starting their is a sandpaper like sound. This whole thing is bugging me as I paid about $1,300 or so for the clutch assembly not including labor for installation. I am thinking of just putting my stock clutch back in. Don't think the distributor will do anything for me.

Hard to say. He claims he cannot do anything with the vibration. Spent a lot of bucks on the clutch and he suggests I could try to sell it to someone else. Oh well. I have decided to put my stock clutch back in, as the wear was negligible and showed no apparent signs of slipping. An expensive lesson for me. Appreciate your comment as well.