The effective length of a stem is a function of both its actual length and rise. Rise essentially offsets length. So a 100 mm stem with a 6 degree rise may be the same effective length as a 90 mm stem with no rise. The difference between a 70 mm and a 120 mm stem is relatively significant, regardless of rise. Same with the wrong fore/aft position.
I'm not sure you really need to get overly bogged down on this however. Start with your local fitter's suggestion and have him put a 70 mm stem on your bike. Ask him if the shop will exchange the stem if it ends up feeling too cramped. If you feel cramped, try the next size upask him if you can try a longer stem (go up in small intervals). You can also increase your options by getting a riser stem that can be "flipped."
As for saddles, Terry makes various "Butterfly" models. Each are a bit different.
I agree that you should get fit properly on your bike before you start auditioning saddles. Fit affects how your're sitting on the saddle. For instance, the wrong saddle height can make an otherwise good saddle feel awful.
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