Best 845 tube out there?

I am running a pair of Cary CAD-211AE monoblocks with the standard no-name Chinese tubes shipped by Cary. Whilst I am happy with the sound, I think I should buy a pair of 845's to keep as backup in case something happens to these tubes.

Because I will need to buy FOUR of them, this rules out any tube that sells for stupid money (e.g. vintage RCA 845 tubes).

The only current production 845's I am aware of are:

- Shuguang 845 "standard"
- Shuguang 845B
- Shuguang 845C
- Shuguang PSVANE 845
- KR Audio 845

I have found reviews of the Shuguang 845B and 845C, but there is virtually no information out there on the new Shuguang "psvane" 845. Has anybody heard this valve, and is it a noticable improvement over the 845B and C? Also, what do people think of the KR?