My dad in law has a Z4 and I will never change my S for a Z4 unless I'm looking to switch to automatic, that's the only way I would...

 

Go from a 2800 lb. sports car for a 3500 lb. boulevardier? Only if the S2000 was never the car for you in the first place...

 

This quote. Well-played.

 

The z4 is a luxury cruiser. It handles like a boat, albeit with a great motor. the z4 is a horrible replacement for the s2k. Get the older Z4M as a s2k replacement.

 

 

I test drove an 08 Z4 before I bought my S2000. I didn't like the ride or handling and frankly the car had one strike against it from the start. I'm not a fan of the looks. Too busy on the sides IMHO. I think the one thing the Z4 has over the S2000 is a buttery smooth engine with much more torque anywhere in the rev range. But as a total package including price, the car just didn't do it for me.

 

I like the way the new z4s look but there are more desirable cars for that type of coin IMO.

 

i had a chance to drive a Z4 maybe 6 years ago, so I am talking the soft top version with the 3.0. Nice gearbox, nicer lined top, better stereo, more quiet in the cabin, looks are subjective, resale sucks based on cost new, fun to drive ....I would rather have my honda price independent cause it is not ...bmw costs more to own and drive and you can't do much yourself, the honda speaks differently to me. I am not ready for an automatic yet. Not a bad choice.

 

That makes absolutely no sense to me. I drive an S2000 because I can't afford a supercar. My wife has a Jetta Sportwagen because we didn't want to pay for an Audi or BMW wagon. Almost every car is a compromise, so just judge it on whether it's the best car for you within your budget.

If you really care what somebody is going to think of you because you can't afford a 911, you've got problems.

 

I like the Z4 especially with the I6 turbo and the retract hardtop, but no stick? Hmm. Still an awesome car though.
I'm with most folks here in that the boxster is probably the better buy, but I would just imagine it being a pain in the butt to work on (no experience) which translates to higher repair/maitenance costs, but the bimmer has that going for it too.
If I were leasing or planning to own in the short term, I'd go boxster. I really don't see it as a poor man's 911, rather I look at it as an awesome detuned car so it won't hand the 911 its ass. With that said, I'd rather have the cayman since I'm more of a coupe guy anyway.
But to answer your question more directly, I don't see a problem with going from Z4 to an s2000. I mean yeah you give up some things (rawness, vtec yo, all the typical pro s2000 banter) with the S but gain alot of other things (power, luxury, badge, hardtop, still handles ok, etc) with the Z4 which to alot of people makes it a better car. So if you could swing it and it speaks to you, why the heck not?