I own three of the plastic tenor models mentioned. I’ve owned my 300 Yamaha tenor since 1978 or so. I upgraded it a few years ago with a tail piece that had the C# key. The first years models only had a C key. I own both the 211 and 511 Aulos Symphony tenors and play two of these instruments regularly. My favorite is the Aulos 511 followed by the 300 Yamaha. My Yamaha is pulled out when I have to hit high C’s and D’s regularly. It is a little more reliable than the Aulos 511 but not much. I like to play baroque flute music on my tenors and flutes tend to play up a lot. My Aulos has a better tone in my opinion. That said I own two Aulos 511’s and they don’t sound exactly alike. There may be more than one mold being used to make these and of course molds wear over time and that will make a little different sounding and playing instrument. I own a Hottetere Moeck tenor which is a great sounding tenor and plays very easily on its highest notes. But I still play plastic tenors a lot because I love their playability, sound and reliability. The only problems I’ve had with these recorders is them wearing out their tenon joints. I eventually filed grooves around the tenons and fitted the appropriately sized O rings from the hardware store. This solved a bunch of problems because I now had airtight tenon joints. The instruments play much better with airtight tenon joints. I recommend both the Yamaha 300 series tenor and the Aulos 511 tenor. Buy one of each, they are some of the best and most inexpensive real instruments on the markey. I hope this discussion helps.