You know you won't ever be satisfied until you try them both. Just do it now and get it over with.
I have neither, but when I was shopping, I was impressed with the weight, feel, and overall quality of the Progress (minus the plastic knob). The Futur felt a bit cheap and sketchy to me. I don't mean to offend those who love their Futurs, but to me the adjustment wasn't as smooth as I would expect and it didn't feel worth the price.
A Progress with a cooncatbob custom handle/knob conversion is probably going to be my next razor purchase.
After starting off years ago with a regular Progress and eventually moving to Progresses w/ and w/o cooncat bob upgrades, and a regular and extended mergress as well as the chrome & matte futurs I find that, for me, the futurs offer a smoother shave and more control with a wider blade assortment than the progresses seem to.
I'll always keep the Mers and Progresses in my inventory, but if I had to keep only one adjustable I'd probably keep the Future and switch between it and a slant.
My (sledge hammer) Barbara Pole Slant is a 1/4 inch shorter than my Long handle Progress. Sorry no photo for you.BTW, can anybody tell me how long the long-handled Progress/Mergress is? Is it about like a 38C? Longer? Shorter? Thanks.