Why not take some lessons from a piano teacher who can give you representative pieces for each of your technical difficulties at all levels?
Good question, let me see if I can elucidate.
This post has been up for almost a month. This forum has 1000s of members. I can't readily identify how many of those members are actually teachers but at least a significant amount of the posters here probably read the the Teachers forum section. My reason for pointing this out is to show that in terms of collective knowledge this site has sigficantly more than the small city in which I live. Here, we have a large university with some incredible piano teachers; all of whom are only teaching students that attend the university. The next level of teachers in this town are the graduated students of the aforementioned teachers. One of these is my current teacher.
I was not happy with the advice I was receiving so I decided to solicit advice from a larger body of knowledge. So far, to date, here is the advice received:
Get a syllabus
Play Bach
Get a teacher
As a result of the first piece of advice I decided to embark on a project of making my own syllabus. I gathered all (well maybe not all) of the postings on Piano Forum that indicated the specific levels of piano pieces and I compiled them into a spreadsheet. This spreadsheet allows me to look up piano pieces by grade level (I made this spreadsheet available to the forum. It's in the Repertiore Forum under the heading Graded Repertoire). I am currently reviewing pieces from that list. However, the shear abundance of pieces (currently numbering more than 1300) makes the task daunting.
As a result of the second piece of advice I have done nothing. Not because I doubt that playing Bach is beneficial, on the contrary, I simply don't have the experience myself to identify WHICH Bach pieces would help me towards my goal of playing the Beethoven Pathetique. This lack of musical knowledge about which pieces lead to which pieces is the reason I asked the question to begin with.
As to the third piece of advice:
I have come to the conclusion that there are very, very few teachers in the world of piano who can identify what the main technical challenges are of a piece and then know and understand what "easier" pieces could be played that help develop that specific technique. Unfortunately, my teacher is not one of them. This is exactly why I posted the question here in the first place.
I believe, Anja, that you have formulated the question more succintly than I did

so I will ask it again here:
I want to play Beethoven's Pathetique.
So far, in Movement 1, the most challenging parts for me are:
The LH octave tremelos
The hands crossing over
The section where both RH and LH are playing the broken chords in ascending/descending motion (don't know if that makes sense, I'll review the piece and give measure #s when I get home)
SO:
Let's assume that the Pathetique is a Grade 7. Can anyone give me representative pieces for each of the above mentioned technical difficulties starting at Grade 1 and going through Grade 7? And, in so doing, can you identify which technical difficulty each piece is addressing?
I am not interested in learning technique for technique's sake and am therefore not particularly interested in Hanon or Czerny. Although, I have heard that Czerny wrote some of his "studies" to work on the technical difficulties of Beethoven's Sonatas. If anyone knows which study ties to which Sonata that could be some very useful data.
Anyone?? Et tu Bernhard??

Thanks a million,
Jef