What sort of life can be expected from these Al?
Obviously I'd swap the bushes out for poly and gm before even considering fitting, but others may not be in the same position to do that, with long term ownership in mind. 
Having said that, it does make a change for a manufacturer to actually put their name on parts at this end of the price range.
Drop links and rear bushes lasted 20k on mine, but I'm not exactly gentle with it... At that price, they might be the difference between scrapping a car and getting another two or three years out of it... 
Think they have a reasonable warranty too... Will post link up when I get home 
Ok, and for others reading, you use poly on the front bush, which means removing the original rubber bush?
Yup, fitted bush out, poly in, fit to car

same could also be done with rear bush and ball joint rivets if you really want to plan ahead...
Link as promised...
http://www.ebay.co.uk/itm/WISHBONE-SUSPENSION-ARMS-SET-KIT-VAUXHALL-OMEGA-B-NEW-/370974895651?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Car+Make%3AOpel%7CModel%3AOmega+B&hash=item565fd3ae23&_xatps=0.51.51x1400.0.0.0 Warranty info down the page

If you already have polys then it makes sense to fit the to the arms before fitting to the car, but if not, no matter, just get the polys as and when ready for when the original bushes fail

From my own experience, every new arm I have fitted since the 2011 Lakes meet has been poly bushed prior to fitting, including the ones in the link above, so I cannot comment on the wear rates of the front bush, but I would expect these parts to last 20k miles

Whilst that isn't great, they are more durable than the prices suggest ime...