[mikefocke]

It ultimately comes down to what you like and what is important to you.

The Z4 and Boxster are very different cars in their driving dynamics. If one appeals to you, it is liable the other won't.

After 25 years of driving stick exclusively, I switched to auto just because of the traffic density and my typical driving needs. Then I moved to a semi rural locale but still kept the auto-manual or auto cars I had from the previous crowded roads home.

You don't say if you are looking new or used as the auto trans on the Boxsters for 1997-2008 are very different from the one in the just out 2010 PDK-equipped Boxster/Cayman cars. So my remarks will only cover my experience with the earlier Tiptronic auto/manuals.

I enjoy my Tiptronic equipped '01S. It replaced a '99 Tip Boxster. I'd estimate I manually shift it ~5% of the time (4% for fun, 1% to downshift because I'm driving over some hills and want the added control I can get from the lower gear). There is a difference between the TIP equipped shift capabilities between the early cars and the later ones. On the later ones, you can down shift via the buttons even while in auto mode. On the earlier ones, you had to first move the shift lever to manual mode.

There are even some who race TIP-equipped Boxsters saying their times are better with the TIP than with the stick version of the same car.

I've had other roadsters including '60s Alfas and a '70 914 that were stick shift.

I bought the Boxster for its balance and every day usefulness. I did drive a BMW Z3 but I was very quick to dislike its handling...in fact I doubt I covered 2 blocks before I returned it to the dealers. OTOH, I bought the first Boxster I drove. I drove more powerful cars (think 'vette), never felt they did for me what the Boxster did. When I totaled my first '99, didn't even consider any of the dozen other cars I had driven when making my first selection, just replaced it with another Boxster. I'd wager the Boxster has a very high degree of people like me who buy another.

In fact I just last night went out for an hour run on rural 50MPH winding 2-lanes just to drive in the spring air. Spun those revs up to 6500 once it was warmed up just to hear the sounds. Always felt it was a better car than I am a driver.

Go drive samples of each. See if the car appeals to what you want in a car, your wants/needs may be different.