I bought new spars for my 18m Phantom today. The shop had them in the same diameter as my Synergy's but my Phantom had slightly smaller ones. I chose to go one size smaller to be sure they fit the pocket.

The new set have a slight bit more flex than the Synergy ones but are still very stiff. I used them today and they performed perfect in about 8kt winds. Should I be watching for anything if they have too much flex ??? I never paid attention to how my thinner original Phantom spars flexed ? These may be the same ? Anybody have original Phantom spars that can comment ?

It should be ok. You may get some slack time due to flex in turning when you get the kite out in a little more wind. I would be careful jumping till you know they are going to be solid. Wait a minute, you only weigh 98 lbs soaking wet, you should be fine. :D

Mostly just watch for flex mostly. You don't want them breaking and going through the spar pockets. That would be my biggest concern.

I guess I am hoping to here from somebody that can confirm for me that the original Phantom rods were a bit more flexible than the standard blue ones with newer kites?

It's true that my light body isn't as hard on gear. I have been flying with a knot in a set of lines for a couple of years now and seem too light to break it?

The ones that are in my Phantom 18 are the originals, they are pretty stiff. Seem not to flex while in the kite.

I used some thin aluminum replacement tent poles in my venom 13 and they are incredibly flexy at length. I haven't noticed any appreciable degradation in performance, but I bet I would on bigger kites. The original phantom spars seem slightly more flexy than my carbon spars, but not much (at 15m).