I enjoy my CQT but you need to check out the Smith& Wesson 1.5-6 shotgun black powder scope. Like 140$ delivered form CDNN Investments. I put one on my FN/FAL and really found it to be quite good has a little more power when needed, clear glass and a good retical, only problem is mounting it ,it has lots of eye relief, I am going to get another one to put on my wifes AR. I've taked to other two other shooters into them and they have no regrets.
As far as bbl. I've been running everthing from 14.5"- 20" and I really like the shorty out to 300yrds real quick handling and easy for off hand shooting. my wife has a 16" & 18" and I don't think the extra weight is worth it for 300yrds and closer and my 20" is mainly my long range gun, 600yrds +.
Just my thoughts