I think the element affects flavor the most is the carto/atty. I've tried quite a few and I've found the IKV Fusions produce the best flavor for a carto. The IKV i06 atty produces the best flavor I've EVER found.
Wharf is correct. The problem is that all attys and cartos are not equal. The cheaper attys are inconsistent with performance and quality. I have some cheap Eastmall 510's that I have been using it has been hit or miss with these attys. Some are great and some are crap. My Cisco 306's have been awesome. I have some that have been in use for over 6 months. The fusions seem to be the best cartos that I have used so far, and the IKV i06 atty is a all around top performing atty.
Coming from an ego to a IPro you should be able to set your voltage of the IPro close to the Ego if not exactly the same voltage of the ego. But from what I have found is the the Ego may not allow the same amperage as the IPro. Even though you have the IPro set to the same voltage as the Ego the IPro will allow the atty to draw more amps thus increasing the wattage. This will change the flavor drastically. You might have to go with a higher ohm atty or carto like a 2.5ohm or higher.