... anyone got experience of them?

My rear wheel bearings collapsed on the way back from a rally last week, I was AA'd back home. The drive side and sprocket carrier bearings were totally mushed, the exhaust side looks OK but will be replaced anyway.
I have cleaned up the housings and bought new bearings as recommended. Fitting the wheel bearings won't be a problem, but the sprocket carrier bearing is proving difficult... it has a slightly larger inside diameter, I presume it's because it has to have the inner shell removed and the ball race and outer shell fitted to a flanged spacer. I'm presuming this because this flanged spacer has new metal smeared over it, from the melted bearing.

Am I right in thinking, I have to pull the new bearing apart to fit it onto this flanged spacer?

I did consider missing it out and fitting another bearing, the same size as the whel bearings, instead... but then I'd need a new plain spacer between the wheel and swinging arm. I think.