Soft or hardshell rain pants?

I know the differences between hard and softshell tops, but I am in the market for new rain pants that I can wear during downpours while hiking and while doing some winter hiking/moutaineering. My only experience is with hardshell pants. Would you recommend I try softshell pants? I don't have a problem with sweating on the lower part of my body (I usually just have a base layer in the winter), so the main benefit would be eliminating the swishy noise of hardshells. Also, are softshell pants more durable when it comes to crampons?

If you need to stay dry in a downpour, then you already know the answer. Softshells are fantastic when the only precipitation you expect to encounter is light powder snow (think spindrift, and blown snow). I've climbed a fair bit of ice in softshell pants, and they tend to hold up well, provided you're not stabbing your calf every other step. No pants on the market are up to that abuse, so don't bother looking.

The reasons to use softshell pants are identical to the reasons to use softshell jackets: you won't be getting wet, you need wind protection, and you'll be moving fast enough that any laminate solution won't breathe enough. If these don't describe your needs, you should stick with a hard shell.

Good softshell material will hold up to abrasion and cutting much better than hardshell materials. I have a set 7 year old Schoeller WB400 pants and jacket that barely look worse for wear despite many vertical miles of abuse. Not even any little crampon nicks. I've never experienced a hardshell that could handle more than a few abrasive offwidth pitches, or one good crampon snag.

I get the impression that you'll be carrying these and putting them on if/when it rains? If so, get a good 2.5 or 3 layer shell trouser and you're good to go.
Soft shells are great for wearing all the time if it's cool enough, but they don't offer enough protection to warrant being carried around.