I use the level 77 Method and overall it does what I expect. I tried the upper level putter on the free rental weekend and saw only a marginal benefit - on longer putts.
Where the Nike is an odd putter is under 10 feet - it is essential to give it a couple more feet power as it is "soft" under this distance.
The key is why you are not sinking more putts. If it is lack of mapping, changing balls constantly etc, the fix is easy, well hard work in mapping lol.
If it is due to mis-reads or not hitting the ding then perhaps you need to do further research or the latter, a rethink.
We all go through troughs but changing a putter is not necessarily the correct fix as it is probably not the putter, but the way you are reading it or executing the putt or leaving it too far away or on the wrong spot on the green.