I would go with the Eclipse just because they come with a 3 year warranty whereas the Clarion only comes with 1 year and 2 years on the Pro Audio Series. The Eclipse also has ESN (the security feature) that if someone "borrows" it they can't use it without the code and they have even sent out new decks to people free of charge right away and they deal with your insurance company.
I've used Eclipse for the last four years and I've been very happy with them. They are expensive, but if you have it installed by an authorized dealer you have your three year warranty. One year if you install it yourself or buy it off of the net.
I've had 4 Eclipse head units and they've always been reliable and have very good sound quality.
Clarion CD players skip waay too much. I think Clarion's idea of anti skip protection is sticking a few rocks inside the radio so the CD doesn't move. Clarion is one of the few audio companies that their products have gone downhill in quality.
Eclipse. They are also the only one who actually has a functional anti-theft security system (ESN). Also, I'm not sure how many are still there, but many of the old school Alpine engineers moved to Eclipse in the early/mid 90s.
Well I have had 3 clation decks within te last 5 years and only had 1 problem what I caused. I have never had a skiping problem esp. with their disc changers. That thiing has skipped on me 1 time and that is amazing considering the roads here in detroit