Well the IQ tour pearl is essentially 1 step down core wise & 1 step down cover wise.
Opti- R2X / Tri sphere core (strong)
!QTP-R2S / C3 control (tour diff)
Where it would work for me....
I can usually bowl 2.5 games with a fusion....I usually struggle to finish the 3rd game out...10 pins, 4 pins, etc. If I had a slightly weaker cover...I'd have it made...