We run 52" decks. I have never run a 61" on a Tiger Cat but I have run more than one 61" deck on Turf Tigers and in stemmed grass the 52" will out cut the 61".
It is hard to beat a 52" deck on a Tiger Cat. They are tough kitties.
Test ran a customer Turf Tiger yesterday after doing repairs. Had the Kohler EFI 26.5 hp engine with the 61 inch deck and to me it seemed underpowered.