The 8v has the bottom end from the Phase 2 engines, when the clio got face lifted for phase 3 then the Diet Engine was introduced. I think it all depends on whether you have the Diet engine or not.
But for what its worth, I have a 1.2 8v Diet Engine and thought about how to make it run a touch better, I called Demon Tweeks and order a K&N air filter, it now sits a lot better on motorways and I have beaten my mates 1.2 16v off the lights numerous times.
From what Ive heard of the 1.4 16v its better to stick with 8v as the coils tend to go quite regularly and they are darn expensive.
Just keep with the 8v and K&N it