...actually vs the old 6.3 wich included the 2.5'' midrange (also known as Morel CDM-54  ). Although i've heard many saying the diference in sound quality between the 2 setups is almost imperceptible i must say i have been absolutely astonished by the result. There is a HUGE improvement in adding the 3rd way. Now...there is no doubt 6.2 is a pretty good setup too and if u listen to 6.2 and 2 days later u listen to 6.3 ( perhaps on the same car-amp-HU...or not) the brain will forget and the difference will fade. What i did because my HU allowed me was to simply compare the 2 setups at a simple touch of a button. The Clarion DRZ-9255 unit has separate outputs for high, mid and low. My speakers are located as follows : woofer > lower-rear side of the front door, mid > on the corners of the dash, oriented towards my ears and tweeter > A pillar, 5cm from the mids and oriented the same way. I will put some pics later ! What i did was to save 2 settings on the memory of the unit :
 
-Memory 1 > 3 way crossed at 400 and 4000Hz
 
-Memory 2 > 2 way crossed at 2500Hz ( i set up the gain and filters for the mid in such way that it won't play > HPF point higher than LPF and gain at -24db)
 
I used different types of music and asked for the opinion of some respected home audiophiles. We all agreed that it was a dramatic improvement in SQ between the 2 of them. To be more specific :
 
- Incredible presence and naturalness of the midrange > in comparison the 2 way seemd very nasal, diffuse, narrow and somewhere on the background
 
- The focus was amazing ( just like in high-end home systems ) > the voice was a spot on the windscreen instead of a zone like with 6.2. I've listened to a celtic song with 2 female voices and i could almost toch both voices. They were THAT real and located 30cm from each other on the windscreen and 4-5m in front of me! Height was just the same as my ears ( before it was 20cm lower ).  
 
- A big improvement was also with the piano and drums. They were very present and just in front of me unlike before when they were clearly coming from the doors !
 
Hope this review will help u decide between the 2 setups on the future! Cheers ! Sorry for writing this in english but i copy-pasted it from another forum since i was too lasy to translate it into french    ! Please let me know if u don't understand and i will translate it for u !

after reading you,I just wonder how expensive is the 6.3 in your neighbourhood.the choice of the 2 chanels version is mostly a question of cost for most of us and we would choose the 3w for the same price...
the other components(source,ect) of your system are quite good,so it explains why you can extract the best performance from the 3w.the 2w might be good enough for everyday listening when only using passive crossovers?..

Oh...but it is good enough for a daily driver. It's even more than that. Still...if u're a freak and want to get as close as possible to perfection ( in this case a vary expensive home high-end system), u will need to go 3-way. I'm preety sure now that those who said there is not much of a difference between them were wrong because their HU just didn't allow them to compare the 2 setups in a matter of seconds. As i said, the human brain forgets preety fast and in the case of Ir6.2 wich is already a good setup, it will perceive it as the correct sound. It's only when u switch to the 3-way in a few seconds that u realise how wrong u are. I did a little experiment : I switched the memory back to the 2-way and realised the difference instantly. Still...after one hour of listening with the 2-way, my brain just got used to it and found it to be normal and good sounding. Of course, we're talking about good to very good components here. My brain will never get used to Sony speakers as being natural sounding !