As we know- several factors are responsible for stone clearance by RIRS. Biggest problem in RIRS is we break the stone & then rely upon nature to clear the stones. Hence for clearance, we have to ensure that 

1) stones are dusted - new machines do that well, 

2) fragments/powder do not remain in awkward calyx - which is difficult to drain. 

3) LC stones are notorious. - if the remain in that calyx - difficult to clear - reasons same as post ESWL. 

This factor is now important as with thin FURS (7.5) especially disposable - one can be bold to reach LC & with availability of this fibers - 200 or 150 micron - even LC stones can be dusted in situ rather than relocating. 

This has lead to open another chapter for discussion - how fragment clearance can be achieved after RIRS for LC stone. This article addresses this issue. They have give a position & in randomised setting found to have better clearance. 

However I feel, clearance during surgery is one thing & clearance after surgery is another thing. We have seen when we fragment large pelvis stone, sand goes in LC & then later does not clear. We have had instances, where we had to do puncture was for such dust in LC which some times does not clear. Even in ESWL we know that stone is well fragmented but does not clear because of LC is notorious location. for obvious reasons. 

Authors have partly addressed this problem but I feel big stone in LC by RIRS will continue to have poor clearance rate whatever position you give. 

PCNL scores over all other modalities because fragments come out on the spot. 

RIRS may be glorified ESWL for LC stone - and whatever position you give, it is unlikely to solve the problem. 

However I am open to criticism & discussion