I do not know if the cost and balance of custom tips are worth it in the end, it may for some ? I'd like to share my experience regarding the fit.
Firstly, I always had good fit with sony iems so I thought the ier-z1r would be a no brainer. I was wrong.
Right after purchase, insertion was quite painful. It felt like inserting cutlery in and out. I thought every day that I would have to sell them but I was subjugated by the sound.
During those 6 months, I went through a learning process thinking of changing tips, rotation and depth insertion.
Changing position and ear tips only relieves the pain on a hot spot before an other spot of the skin starts "working". It's a necessary learning process but often led to drawing early false conclusion ; concluding that the new tips sizes "finally don't fit", until the pain was gone again. The skin being less sore allows to insert deeper and rotate some more until it hurts again. Alternating deep insertion and only closing to get a seal. I'm certain some concluded after weeks that the ier-z1r would actually never fit, I thought the same several times.
Changing tips did not actually matter that much as long as all the spots of skin are not yet used to the animal. Actually, it felt like the least comfortable it was, the faster the ears were getting used to them. Also, my right ear was "learning" the ier-z1r faster than the left one.
I used Small-size for a long time but I'm surprised to now settle with the sony silicon Large tips which I find sound good. I felt like the triple comfort kept my ears in their comfort zone, not allowing the skin to adapt to the pressure points of the iems.
The situation improved week by week for... six months using the ier-z1r every day. After the 6month I am now able to wear it without discomfort for unlimited time. The skin got tougher and adapted, whether for tip pressure, cable plug or cable. The production of ear wax was important during the adjusting time, but now they are not producing any! The iems remain perfectly clean. I was tempted to buy other tips but since the discomfort kept evolving, I waited and rightly so. Try to avoid buying every tip brand and sizes if your skin is still too soft.
Unlike most 20€ iems, yes they are heavier and require some seconds to be properly positioned and inserted. I thought that these things were not designed for the ears, rather for sound since it was that painful. But my judgement changed. So there is still hope even if they fit terribly like it was the case for me.