OP needs to tell more details ... like, intended use of the bike ...
For serious track / racing use, as Koko64 stated, there's always the chance of frame sliders doing more harm than good (at least, some people believe that).
BUT, if you are a street rider, having frame slider WILL pay itself when the tip over happens the first time.
http://www.ducatimonsterforum.org/index.php?topic=76461.0Also, keep in mind that frame sliders are supposed to sacrifice themselves in the crash.
What that means is that frame sliders are NOT supposed to be super strong.
No, it's not "more solid = better".
The delrin / duracon (they both are Polyoxymethylene (POM), the same stuff, different brand name) slider part
will / should break if they get hit with more than certain amount of force. (So that the slider won't transfer that impact (energy) to the frame engine mount area.