Good point raised by Andrew with the ratings. Anyone who has read my power consumption thread would see I referenced the Westinghouse website as they have the star ratings online, along with the kw per year.
300L Upright Freezer
is rated to 525 KWhr/yr, which @ 25c per KWhr = $131 per year
320L Chest Freezer
is rated to 400KWhr/yr, which @ 25c per KWhr = $100 per year
So using my local power cost, you would save $31 a year with a chest freezer. But with a homebrew fridge we generally open and close the door less, so the factor of cold air dropping out of an upright will be reduced, and I believe reduce that $31 difference even more.
I use a chest freezer for grain storage, so the only time I'm lifting into it is when I get a new bag of grain. I know they feel heavier lifting into the freezer then you expect. I've got 320L upright fridge holding 3 fermenters and a 320L upright freezer I use for kegs, I do find it a lot easier to put them in than leaning over the side of a chest freezer.
Also a few good other points raised, when you look at reliability the total cost of ownership comes into play and not just the power usage. Especially the one about damaging your back lifting into and out of a chesty, do some permanent damage to your back and I bet you would wish you didn't opt to save a couple of dollars.