I know what you mean. I am using stadimeter practically 80% of the time. After I installed that tiny cross hair made by Torpedo ( thanks again, buddy) my distance accuracy is like 150m on 5000-7500m range. Just unbelievable. Another thing - not to start to take mesures for solution earlier than when target in position of about 45 degrees AOB (approximately, of course). Track it for about 15 degrees - and you will have very precise AOB, speed and naturally last distance. Another mistake that I see people make on u-tube videos: while they struggling to put AOB periscope still following target. That's a big no no!
Immediately after taking second (or last) measurement using stadi - unlock the periscope as quick as you can! Then take you time dialing correct AOB and speed. When you ready to attack (usually target reaches 60-65 degrees AOB reading in TDC, adjust distance for couple of hundred meters less (depends on total distance - just practice makes it perfect) and go ahead - put scope back on the target.
I was hitting warships on distance of 8900m with TI torpedoes using nothing but stadimeter.

As for RAFOB - it was perfectly calibrated but I were shuffling mods back and forth and it got totally screwed up. It is useless right now with mills that I have. Anyway RAFOB is only good for very slow moving targets. I work very fast with it, takes me like 10-15 seconds to calculate everything but visual have to be very precise and it is very hard to do it without pausing the game. And I don't pause ever (as you know), so I hardly use it anyway.