Yes.. it's sad to see the TNC-Pi go and I imagine the new TNC-9k6 version too! Sometimes some hacks could have been done like putting a modern surface mount PIC chip on a carrier board to make it compatible with the legacy thru-pin chip style but maybe it wasn't worth it. The new TARPN board looks like it could be very impressive but time will tell on it's decode rates. I also Dana K6JQ has an impressive TNC project too with decodes comparable to Direwolf... if we could all just convince him to release it!
Direwolf is extremely impressive on it's decode rates and I've personally found it VERY reliable. My APRS IGate has been running for 112 days and has decoded 1.74M APRS packets so far! Even on the rare situation of a hang, Direwolf can be made to auto-restart as well as have the entire Raspberry Pi restart if needed. The overall solution can be made to be rock solid.