What's the difference between the 44/52" Fastrak and the 48/54" Fastrak other than the obvious deck size? Additionally, my local dealer says he cannot get the 48/54 until he sells his remainig inventory of 44/52"s. Is this Hustler's policy? Also, I have been considering the Mini-Z 19KAW/42". My 2-acre bermuda yard and surrounding area gets pretty dusty and I was thinking the heavy duty air filter might be better in the log run. I kind of want to make this my last mower purchase for a while (~10 years) if I'm going spend $$$. Thanks.