I am really wondering if the ordering of the items makes sense on the long way. I think leveling up as fast as possible is not the only important thing. The higher in level you will get, the more you will feel that its also important to take your time.
I have the same “problem” that I have to go through 30 vocabs before I get to the radicals whenever I level up, but I would rather spend one more day and learn the vocabulary to the Kanji I just guru’d than to directly start with the next batch yet again. Kind of like taking a short breath in between.
I also think that in theory it could happen that you start having vocabulary that you keep pushing further and further away because it conflicts with your goals of leveling up. Other than that I only had problems with the sorting script, but that’s just me I guess. This lesson filter looks quite neat though. 
Apart from that I can really recommend you this script that shows you the upcoming critical reviews, which is less intrusive my opinion. [Userscript] Forecast details / critical reviews