There is no questions that they are much better and worth the investment.
In your case the question is are they neccessary? What is your setup? How much spring pressure? How many rpm? etc.
I prefer the Jesel's over the T&D's. If you don't have a really radical setup and are running less than 700#'s of spring pressure over the nose, then you can get away with the Sportsman Series rockers from Jesel. If you are past the 700# mark, or running much over .700 lift, then go to the Pro Series with the one piece rocker stand. Hope this helps.
Give me a shout if I can help. I'm a WD dealer for Jesel.
Eddie

Agreed, I also prefer the Jesel's in race type engine applications.

But Eddie is right, the cost discussion depends on your application regarding RPM / spring pressure / camshaft profile.

For example, I won't bother spending the money for the Jesels on the 454's in my pleasure boat because I'll only turn it to 5500 RPM max. The shaft mount Jesel's are overkill for those engines for me (but not knocking anyone who would choose to run them in that application).

But on the other hand, I have multiple race car engines that turn consistently to 8500+ RPM, and the shaft mount Jesel's are a no brainer (and in my opinion a necessity) for a stable valvetrain in that application.

So the 'are they worth the cost' question depends on your application and size of your wallet more than anything else.

My humble opinion for what its worth

540x2 afr 315 cnc bob is working on cams around 650 lift 5800-6000 rpm already have comp pro mags should i jest use them with gerdles

Agreed with the one piece,

that is where I have seen them break, at the weld.

You are right on the verge of where I would use them. If you think the engine will pull to 6000 rpm and if you think you will see that rpm on a somewhat regular basis, then go with the shaft rockers. If you are going to turn 6K rpm once in a blue moon, or if it will only pull to 5800 rpm, then stick with what you have.....because you have them.
If you are starting from scratch, then the shaft rockers aren't that much more than a good stud mounted rocker with stud girdles. I don't run stud girdles. Quite simply, if I think it needs a girdle, then I just put the shaft rockers on.
You can spend up to $750-$800 on studs, guide plates, rockers, girdles, etc. A set of the Sportsman Series Jesel rockers are about $1000. That is a no brainer to me. That is $200 well spent. Good luck.
Eddie

Whats the service life for shaft mount rockers?