I don't understand whether you are asking for feedback on the procedure design, or its representation on the instrument plates.
If its about approach design, I'm not sure that many of is have an opinion. We trust that the constraints of lowest safe altitudes, glideslopes, turn rates, error allowance etc means that there are not a huge number of degrees of freedom in approach design and we trust that AsA do a safe conservative job of it. I'm not sure how to judge how good AsA are at this - especially RNAV NPA approaches which pretty much draw a straight line back from the threshold.
And don't forget that reversal approaches (NDB , VOR) are now pretty much the approach of last resort. The ease of runway aligned RNAV approaches and lower MDA's combined with the increasingly poor maintenance and poor reliability of NDB & VOR beacons means that they are becoming less relevant.
If its about the plates, I changed to Jeppesen some years ago when AsA changed format to the current A5 side hole sheets. I didn't like the unilateral way it was introduced without seeking real world feedback, I didn't like the print quality and the paper format screwed up my flight bag / cockpit system. So, I thought if I'm going to rearrange my practices, then I might as well move to Jepps which were used by all the serious IFR pilots that I respected.
The key things I like about Jepp charts are:
1. The print quality is better, with better use of shading
2. Jepp use varying type faces and font size to make the important bits easier to read. Most times when you are flying an instrument procedure for real, the cockpit lighting is less than ideal (ie in cloud, or rain or at night).
3. Whether its real or not, Jepp seem to have less volume of updates. They seem to replace less pages because of mistakes.
4. After I changed, I learned that Jepp have a structured process for making changes in chart format. They start with studies in simulators, then move to trials with a panel of pilots drawn from airlines, corporate & private flying.
For your research, I think you could get a lot of useful information by constructing a trial in flight simulators. Maybe use this forum to ask (a different question) about tricky approaches to get a list of different ones to try, then have a group of pilots fly them in simulators. But, remember to run the tests in low ambient light and do something to stress the pilots so they cannot give the charts full attention (like a real approach in bad weather). Also remember that a lot of (non airline at least) IFR pilots are at an age that requires or nearly requires reading glasses. Beware using uni students with good, young vision as test subjects.