As far as the their actual stats goes, I'm not familiar with a lot of the more recent stuff Rogue has done, so she might have reached heights I don't know of. For years though, I felt it was generally assumed that he was more durable than she was, while she had the advantages of speed and flight. Strength could be argued, but I would generally pick Colossus tbh.
As far as the absorption thing goes, this is what I was able to put together:
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Uncanny X-Men #179 This is the first actual absorption of Colossus by Rogue. After being heated and then subsequently cooled by Pyro and Avalanche, Colossus is trapped in a kind of "frozen" state. Rogue's absorption of his power turns him back in to his "Human" form, allowing the Morlocks to heal him.
https://imgur.com/M34nPjl
https://imgur.com/4GMDNXj
Uncanny X-Men #194 While fighting Nimrod, Rogue absorbs the powers of both Colossus and Nightcrawler so as to better fight the future Sentinel.
https://imgur.com/SGDPwPF
X-Men and Alpha Flight #1 During a Danger Room session gone wrong, Rogue is struck and falls from the air. Colossus being Colossus, he puts himself at risk to catch her and their skin-to-skin contact causes her to absorb his powers.
https://imgur.com/KR7XpOj
Uncanny X-Men #208 While going up against The Hellfire Club, Rogue accidentally absorbs Colossus's powers while trying to prevent him being sunk in to the Earth by Harry Leland.
https://imgur.com/FIHcMy9
Uncanny X-Men 247 Rogue absorbs Colossus's power so that she can add it to her own during a battle with Master Mold.
https://imgur.com/PWZ8SW2
So already we have five instances of Colossus's powers being absorbed by Rogue, all written by Chris Claremont. There can be little doubt of his intent as regards Colossus's vulnerability to Rogue during that period. It should be noted that the last time Claremont had it happen, in Uncanny X-Men #247, was AFTER Colossus had undergone his first upgrade in the wake of the Morlock Massacre (Uncanny X-Men #211).
Back in 1985 there was also the X-Men Heroes for Hope One Shot, which, while obviously not canon, was overseen by Claremont, so it serves as supplementary evidence that the person that by and large defined both Colossus and Rogue intended for her to be able to take his powers.
https://imgur.com/XNbe8gq
https://imgur.com/tCJwtUu
X-Men #80 In an issue written by Joe Kelly in the late 90s, we see Rogue absorbing the powers of Colossus (among others) so that she can fight Cerebro's X-Men.
https://imgur.com/32BcvpK
https://imgur.com/xt7odsb
X-Men Legacy #235 Takes on the powers of Colossus and several X-Men so as to better protect Hope Summers in an issue written by Mike Carey.
https://imgur.com/0dwN6E3
Cable and X-Force #10 Steals Colossus's powers while fighting Domino in an issue written by Dennis Hallum.
https://imgur.com/gLULJrF
So yes, the consensus at Marvel seems to be that, even if Colossus still had the numerous resistances offered by his organic-steel skin, he would not be immune to Rogue's touch. That does not mean, however, that an alternative wasn't considered at one point.
In 2000, during an arc written by Chris Claremont himself where the X-Men fight The Neo, we see enough to hint that Claremont was going to make some changes.
X-Men #100 Colossus in his metal form touches Rogue without suffering any ill-effects.
https://imgur.com/Rh3OnVR
X-Men #102 Colossus has his powers absorbed by Rogue, but this is WITHOUT skin-to-skin contact. I don't quite understand why her powers are going haywire, so if someone could correct me on it, I'd appreciate it.
https://imgur.com/TetBdCx
X-Men #106 Colossus makes it a point to turn from metal to flesh before kissing Rogue, allowing her to absorb his powers. Rogue even comments on the transformation.
https://imgur.com/qQybQP2
X-Men #107 Colossus, in his Human form, takes Rogue's hand, and is subsequently brought low by her absorption powers.
https://imgur.com/7yZvPVB
From that, I don't think it's much of a leap to believe that Claremont, the man that had defined these characters in the first place (he even created Rogue), was at least in the early stages of changing the nature of how their powers interacted with each other. It might not have been carried on by Marvel, but the idea of Colossus's skin granting him unusual resistances is not a new one.