A8/a8l: 2007 or 2008+?
 

I'm in the market for a new car after the timing chain guides on my '05 A6 3.2Q went. I debated doing that repair, but the car has 168k on it and the indy, who I really trust, is quoting ~$3500 for the repair, which involves removing the trans or the engine.

Anyway, I'm looking to move up into an A8. My A6 was extremely reliable, requiring only one major repair to the front end during the 5 years or so I've had it. I'm frankly a little nervous about getting into the A8, although it's been my dream car for years. So here are my questions. Thanks in advance for anyone who can even answer 1 or 2 (I know it's a long list):

1. Generally, are these cars (07 and up) thought to be reliable? Are there any systems that require more dutiful maintenance than others, or any systems that are prone to premature failure/repair? Along the same lines, is the '07 thought to be more or less reliable than the '08 and up (post-refresh) or vice-versa?

2. Are there any additional trouble spots in the A8L vs the standard wb model? This goes for both '07 and '08+. (I'm leaning toward a swb model because the L is a little too limo-like for me at 34 yo)

3. Are there any systems on either the '07 or '08+ that are crazily and/or surprisingly expensive, like $1500 brake pads or something?

4. Is the hydraulic suspension prone to failure or fairly reliable? Are there any tell-tale signs to look for when I'm test driving?

5. Is there any reason other than cosmetics to get into an '08 vs an '07 (updated systems, better engineered parts, really cool new features, etc. I imagine I can buy aftermarket tail lights to approximate the look of the refresh)?

6. Generally for the MMI, which for 2010 seems to have some nicer features than in years leading up to it (bird's eye NAV, etc), can software for more recent years be applied to older cars? Aside from the cool luxury features of the A8, the MMI even in the '08 seems eerily similar to my '05 A6 (or am I wrong?).

7. Lastly, what's a good upper-end for mileage? I'm trying to stay under 70k.

Thanks everyone SO MUCH for any input you can give!

Nick