[Manowar]

At World Products, slightly more than 25% of our complete engines are aluminum block options. The percentage of shorts is slightly less. We have several hundred in use over a ten year period by customers and have virtually zero warranty claims on them and very few issues we've seen on the race engines. It's important to remember that unlike other builders, we manufacture our own castings and build our engines from them exclusively.
All of our sleeves are ductile with top flanges and o-rings. All are press fit by heat/cool method. Our brand new Warhawk LS engine uses this method which drastically improves GM's sleeve installation problems of falling out and/or ballooning. The GM sleeves have no flange, using ribs on the sleeve instead,which is then inserted into the tooling (mold) and the aluminum is poured around it. Obviously cooling causes a dimensional change and often high HP, boost or spray use causes the sleeves to fall or fail.
Further, no issues about thread holes for frost plugs or stud attachment are experienced unless the end-user is careless about anti-seize or proper torqueing.
Iron or aluminum, the choice should not be based on fear of aluminum's properties-all the reputable builders (including us!) offer high quality blocks and can build a trouble free engine for you.