You certainley know when you get it wrong! Any inner position problems will be magnified, so it did help in that sense. Get your inner position right is shooting 101 but if you get lazy it will let you know. Any pulse will give you a fright and stand you back up to start again...
Groups on a whole did become slightly tighter but I'm not going to say it was 100% because of the tube, I think it helped. I had a very good season that year and it may well have been my shooting coming into a period of ascendancy, coinciding with the tube trial (or because of the tube??). I still shoot with it and doubt I will go back to non tubed barrel for the foreseable future. I had a wee stubby tube made for standing but kept the full 12" tube for kneeling, you have to get your position spot on when kneeling with a tube, so again it helped with positioning which helped get better groups which gave me better scores.

I'm waffling.
Did the sight radius gained from the tube help? Yes.
Was that because of the sight radius or because of the magnified error effect making me "GET IT RIGHT"? Hmmmm.

It worked for me.

Bing!

PS. Let me know if that rambling response was of any help at all.