Definitely do the struts if they're available (they weren't when I did mine, and I had a broken coil to replace, so I went ahead and put them on my A4 non-sport struts). I have no complaints about my setup other than the ride height of the non-sport suspension, but I have a line on a set of sport struts that I'll swap in later on.

There really isn't an advantage of springs only vs springs and struts, other than more ground clearance for avoiding damage to the car. And as for the time to do the work, the fronts are more of a pain than the rears. For the rear, you have 7 bolts to remove and they're out. Indexing is by default - they only seat one way and it's apparent when you reassemble them.