Let me put it this way.
When I have a new apprentice with lil experience and I want him to feel comfortable and safe and be able to work safely, quickly and effeciently, they go on the SJ right away.
The Singing tree Ropewrench paired with the SJ and RopeGuide is great fluidity.
The only things I do not like is that it is not midline attachable and replacing clutches. Seldom a problem but can be pain when I need to trade out TiPs or go to short or longer rope. Clutch wear is easily remedied as well with do long descents with my rack or gri gri and short descents with the RW.
imo It is easier, smoother, safer and more predictable than rope on rope. Simply there are less variables to factor in with mechanical.
I find it perfect for my climb style and coupled with a Ropewrench has really opened up a more effecient work climb. Most of the work I do is reductions on maple and oak in Ontario.
If you are going up and down and in and out/lateral or vertical and self tending or descending with one hand and climbing with the other this tool is very good making things easier.
I believe it has helped with some of the joint pains.
What is the key point that keeps you from making the leap to mechanical?
If its the cost, I wouldn't sweat it, if you are anything like me it will be justified in one day of work climbing.
I went full bore with it into a removal and a few minutes in thought to myself how silly it was that I waited so long to get one because once you try it, the realization and the experience of the effeciency of metal on rope is huge. Same thing as running ropes on a bollard or long descents on a rack, RW, gri gri, RopeArmor etc
best of Luck