Do you work for CCP? Don't be naive... It would be extremely easy for CCP to detect ISXEVE. The extension makes no attempts to hide itself (as of this writting).
Wether or not it is safe is a personal decision. Trust your own judgment and don't rely on anyone here to tell you if it is safe or not. It all comes down to risk versus reward. I use ISXEVE on accounts that are less than 6 months old. After the characters get more than 10 million skill points I am very nervous about running ISXEVE. There is no way I would run it on my two year old character.
When CCP starts using detection, I'll let you know.
It is important to know that ISXEVE is unlike any other extension out there for innerspace (or anything else for that matter.) It does not alter memory space at all. In all honesty, it is more like an extension of the EVE client rather than something that augments or changes it.
It would take something very similar to warden to detect isxeve as it is right now. And, that would be very obvious.