But when it comes to comfort the consensus tends to be that they are rather heavy and gets very uncomfortable quickly if you’re wearing them for an extended period of time.
I agree to completely disagree with this unfairly generalising statement.
I was sitting on the fence for quite a long time if I should buy a pair of IER-Z1R or not. I was scared by similar posts here stating that this IEM is too big and too heavy. Based on the photos it also looked like this.
In the end I was even ready to buy it blind. Fortunately I found a IER-Z1R owner in a neighbour country before who made it possible for me to audition it.
When I saw them live, they did not appear too big anymore at all.
So I bought it afterwards. A process of finding the right way of positioning them in the ear and of the right tip size began then. During this time my ears were getting accustomed to the IEM shell.
However, even in the very beginning I did not have any troubles wearing them. No pain, no hot spots, no soars. And I am not any big ear guy really.
The truth is on the other side that I have been using them from the very beginning with the silicone sleeves I bought on Aliexpress to protect my IEMs from scratches. So this might have done the trick as a side effect. Who knows?
I could read in this thread that quite many posters bought IER-Z1R repeatedly. At least one of them has done it even three times. This is a bold statement per se.
Based on my approx. 9 months of daily using my IER-Z1 during commuting I can only recommend auditioning (if possible) and buying them.
Their marvelous sound has been described here many times before.
As far as their fit is concerned, big part of their owners' ears can get accustomed to them and they can learn how to position them in the ear.
This IEM simply needs a little bit of user's patience.
One more thing to add: I have been using them with SONY EP-EX10A ear tips all the time, since a couple of months in M size.