I guess first you have to get access to a block .

I was told the aluminium block would have some movement and reach a settled best after the second or third freshen up . Old wives tale ?
I went iron , yes i got lucky . You have to be more careful with ali to get / keep warmed up . I didnt feel going into stage with a cool block was what i wanted . Iron moving less would reduce this . Just read some of the growth amounts people talk about .
Not sure about ring seal differences tjough that is often brought up . Maybe at higher hp levels than you or i ?
As a daily driver i am happier again with the iron for warm up .
I am na , so cant help with gas
But the extra lbs i could do without . All a trade off .

Tex