I've searched through a lot of threads here, but haven't quite found the answers I am looking for.

I've read in various places that the shocks in the R170 are all interchangeable, but the part numbers are different for the SLK or the XF. Is there any real difference? I saw the discussion that KYB introduced the XF specific number back awhile now. Is that considered the better KYB shock now, or do people still use the SLK number? When people say they put on Bilstein B6's, which number did they actually put on, and is there a noticeable difference and a preference between the SLK and XF numbers?

Bilstein B6: XF front: 24-109987
Bilstein B6: XF rear: 24-109994
Bilstein B6: SLK front: 24-024648
Bilstein B6: SLK rear: 24-024655
KYB: XF front: 553363
KYB: XF rear: 553364
KYB: SLK front: KG4731
KYB: SLK rear: KG4732

I also noticed that the KYB's and the B4's come with the rubber bumpers, but the B6's don't. On an 18 year old car I am assuming I want to replace the original rubber while I am doing this. Is the rubber that comes with the KYB or B4 the right size? What do people do for the B6? "repair kits" are available for the SLK at about $25 each, and are listed for the XF but nobody seems to have them except for a few leftovers at insane prices. It seems like those rubber stops would be the same in a lot of cars and would be really cheap. What is the best way to replace those?

I'm leaning toward the B6 but don't know which model is more appropriate, and could easily be swayed to get the KYB or even the B4. Cost between then is not a big factor. I'm not looking at the Koni because I don't think I will use the adjustment and then they wouldn't be worth the extra cost. I'm strictly fairly normal driving on the street and am looking for a good balance between ride and performance.

Any advice/opinions based on long term drivability would be greatly appreciated. The majority of posts I've found are first impressions, with few long term opinions as they settle in.

Sorry if this is well covered territory, but I can't quite find what I am looking for.