thiel speakers forum

I have Thiel 2.3 speakers purchased in '99.  I am seriously considering upgrading to the newer tweeter/midrange drivers that were introduced later after model numbers over 4700.  I wanted to hear some comments from people who may have performed this update to get their impressions.  How do the new drivers sound vs the old ones.  Would you recommend the change.  What did you notice most after the upgrade.