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Wow, I haven't been on the boards for a while and find this thread. I wasn't surprised though.
To start out, the N52 engine does not have "lifters". Those belong in push-rod engines. They do have HVA's (Hydraulic Valve Adjusters) and they are the cause of the ticking noise you guys are all hearing.
In the beginning of all of this, we were installing improved cylinder heads with an extra check valve installed to prevent the valve spring pressure (no matter what position the engine stops at when shut down, there is always 2 valves that are left open causing spring pressure on the HVA's) from pushing the oil out of the HVA's. This was an interim fix until the HVA's could be re-designed to prevent the bleed down. Now BMW has re-designed the HVA's to prevent the bleed down and the expensive cylinder head replacement is no longer necessary. Replacing the 12 exhaust HVA's with updated ones has fixed every car I've seen so far.
There is no long term effects from this, you could run the engine without making the repair and it would not effect it's durability at all. The noise is just a nuisance, pure and simple. Within minutes of cold start up the HVA's pump back up with oil and all is normal.
If anybody is in the mood for a quiz.........why are the intake HVA's not effected on this engine? A pat on the back for any non-BMW technician that can answer this correctly 
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I disagree with this, as many prior posts in this thread will confirm. One of the first SIBs to address the ticking noise was to perform a bleeding procedure, which didn't cure any ticking noise. A revised SIB was issued to replace the exhaust HVAs. I have had this ticking on my 2008 X3 (I know it isn't an E9x, but same N52 engine) almost since new. The ticking does not stop after a few minutes warm up, it only gets louder. The ticking noise returned about a week after I had the exhaust HVAs replaced, as it has with most of the people who have had the HVAs replaced. A good run on the freeway will cure it for a while, but after a few short trips, it returns. The only repair I have read which solves the issue is a head replacement, which is currently underway on my X3, which the dealer readily agreed to do. I really doubt BMWNA would have done as many head replacements as they have unless there actually is an issue with the original N52 head. As to why the intake HVAs aren't replaced (in most cases), I have no idea, not sure it matters either way.