make sure you fully understand the dangers of dealing with fiber lasers, there's lots of confusion and discrepancy but it is beyond any doubt that it is more hazardous than a CO2 laser.

Have you looked at the Bystronic Bystar? The Bystar 3015 is a real workhorse when coupled with the 4400 watt resonator.

Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS

Just so you know, I work for Prima, so my answer may be obvious. both are good in the automotive market, they are the leaders. I would say there is 1 Key Feature and we do not even make it. It is the IPG Photonics Fiber Resonator. It is the most SIMPLE (easy to own and operate) resonator on the market. Most all, except for Amada and Trumpf (could be some others like Hypertherm) use IPG for low cost of ownership, little to no repair and it is simple. Automotive does not need a complicated electro-mechanical disc device. We use IPG exclusively on all of our 5 fiber laser designs. IPG will make your choice easy.

It depends on what material you expect to cut, especially thickness wise.  If you'll be cutting mostly thin material (10 Ga and less), fiber lasers are a good alternative.  They can cut thin material much faster than CO2, they are more efficient and also requires less electrical power (which is a big advantage in areas or countries where electrical power is limited).  There is pretty much no maintenance, but, you will have to pay a yearly fee for a warranty in case the resonator needs to be replaced (that is passed the manufacturers warranty).  This cost is sometimes more than 1 year maintenance cost on a CO2 laser.  So, make sure to look into that.  

Also keep in mind that fiber lasers can not be repaired in the field (need a clean room).  If something happens to it, it needs to be shipped to factory or swapped out.  I guess in the US, this is not really a problem as overnight service is available.  But this may be an issue in some countries.

There is also the issue of back reflection, which can damage the feed fiber, or the beam combiner (meaning the laser needs to be shipped back for repair).  Most machines will never have this problem, but I've hears some had to have the feed fiber replaced every year, which can become very expensive.

And then, as mentioned by krugtech, there is the danger linked to the particular wavelength of fiber laser (although this would be more for service guys; operators should be safe as long as no safety is bypassed).

The cut quality in thicker material is not impressive; even sometimes in thin material.  This is because the manufacturer needs to make a choice in the diameter of the fiber used.  Most will go with a 100 micron to offer best flexibility.  To cut the fastest in thin material, a 50 micron would be ideal.  To cut thicker material, a 200 micron would be better.  This is kind of like choosing between a 5", 7.5" or 10" lens.  Except that it is harder and much more expensive to change a fiber compared to changing a lens.

So, make sure you get a demo with some of your material; so you know exactly what to expect when it comes to cut quality (especially aluminum which seems to leave a burr quicker than CO2).

If you want a machine that will do it all (thin and thick with best cut quality), a CO2 laser is still the best in my opinion.
If you want a high end fast and expensive machine that will cut thin material 24/7, then fiber may be the way to go.

If you want to see them in action, the Fabtech show in Chicago is coming up.  Pretty much all manufacturers will be present and it seems lots of them will have CO2 and fiber lasers on display.
 

Footstrap- Thanks, that was some really good info! About Fabtech- Atlanta while I didn't see it myself I heard there was someone demonstrating a fiber laser with either some of the covers removed or insufficient covers. Did anyone hear about this? I know some of the other vendors recognized this and complained but I never heard the outcome.

Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS