I have this same piece, and I get this exact thing. I've monitored it to the best of my ability to figure out how to counteract it and get the best experience with this piece.
The "burning" happens from a few things in my experience. These variables directly affect it, ESPECIALLY with the Small Inline. I don't get these issues on my larger piece.
-Too fast of a draw
-Too high of a temp
-Too long of a draw
High airflow convection vapes are going to be a lot harsher. Putting my Herborizer Ti on the Small Inline, I can't draw fast or crank up the temp and draw out my hit. If I keep it to a short burst, I can manage it. Once I draw it out though, it gets very hot like I just burned my throat. To the point if I really tried, I could make it rather unbearable.
My Nano XL is much more gentle. On the Small Inline, on a higher temp, I can do just fine, even with huge hits.
The issue starts to come when I pull significantly too fast (which one never really would with the Nano XL), but more specifically with too long of a draw. This turns what would usually be a smooth experience on a small piece, to something hot on my throat.
The throat can handle some heat, but it's the long exposure to heat that starts to burn in my experience.
The Small Inline is not great for cooling. There is basically no chamber for the vapor to cool down in, and for the most part goes straight to your mouth with little glass contact, and barely any water.
It is still a fantastic piece though, and I'm using it daily still next to my huge piece. I use it on my lower airflow vapes like the Nano XL or Dynavapes, and even my Herborizer still if I know I'm not going for huge rips.
Try to adjust these variables, most importantly for me the length of the hit. A higher temp shorter hit is easier on my throat than a lower temp long hit in my experience.
Or, get a larger piece with more contact with glass to help cool it down further. Having the options are nice, and glass can be so cheap through dhgate.
I hope you still enjoy your Small Inline despite this, and are able to find a way to make it more enjoyable. I absolutely love the function and design of mine, just need to consider how the small piece affects me and adjust accordingly.