we replaced our tec 3 vaporisers when we replaced our anaesthetic machines.We now have two types of vaporiser blease and penlon,the calibration is checked every 6 months and so far out of about 60 vaposisers non have failed.The only slight advantage I can see is that the penlon is alot lighter and easier to handle,but as our machines are blease frontlines the blease vaporisers tend to be used more often.
If you thinking of using one of this type its a good idea to see if they will take your tec 3's as aprt exchange, I know we got a good deal with penlon but that was about 3 years ago.
hope this helps
regards
richard