This is my experience of driving an 2004 Mazda 6 I4 yesterday. One word sums it all: SLOW.
Slow and unresponsive. I don't know how the last owner beat up this car, but it seems the tiptronic is so unresponsive. It literally took 1.5 seconds to change my gear. Normally if I downshift my 3, it would drag my 3 slower and I would totally notice. Not at all for the 6. Seemed like that thing wanted to keep going. I tried flooring it going uphill. Slowww. Handling is not as good as the 3. The gauge looks ugly also.
Now I get why nobody buys the 6 anymore

dL