Let me first say that I grew up with a dad that bought higher-end equipment. He has a 20-year old Kubota lawn tractor that still runs great, and now has a Scag Turf Tiger that is an absolute tank. However, he has a farm and has rougher uses for his equipment. So, I understand the value of commercial grade, and would love the thought of buying something that would last a long, long time. However, I am your typical, average homeowner with an average, 1 acre lot. I don't have much, if any, rough terrain, and I don't have much, if any, thick brush I have to cut into (I have the occaisional honeysuckle sapling that I have to mow over, but we aren't talking about woody trunks). How much more would a 7 ga. steel deck improve the life of my mower? How much more would a heavier-duty transmission improve things? In other words, how long can I expect a nice residential machine to last vs. a commercial grade machine? Is it 10 yrs vs. 20 yrs? Is it 20 yrs vs. 25 years? I can probably buy 2 nice residential machines for the price of a nice commercial machine, so will a commercial machine last over twice as long? Another thing I like about a commercial mower is the bigger gas tank, but if I am mowing only an acre or so of yard, how much gas am I really going to be using? I know a lot of factors go into acres per gallon, but is there a rough ballpark for average residential use?