I ride my omniums in the crappiest weathers. Still didn't change the BB after 2 years, can't complain for 125 cranks and BB all in. Plenty stiff for my tooth stick legs
Got the S-Ones in at first try in Grail rims. Was surprisingly easy, for the second one didn't even bothered to seat it before putting sealant. Just rim tape, get sealant in, put valve core and pump hard.
Everyone here have stems, bars and all kinds of spare parts. Just go to classifieds or say what you need here, it may save you a lot of money