UERM ideally has quicker, cleaner, more linear bass than ES5. ES5 is boosted just a tad as a stage monitor and it hits harder, sounds a bit larger and extends lower.

Tyll likes a little more room gain in the low end than what most would consider neutral. Nothing wrong with that. Plus there's upstream choices and decisions. If I use my Leckerton in low gain, the UERM will hit a little softer than it would in high gain. So listening level and channel imbalance issues could come into play with impressions. As usual, YMMV and the devil is in the details.

One other note, my last UERM custom was returned due to issues which I believe were acoustic in nature due to how they were constructed which included a fuzzier indistinct bass. My latest redo set sounds pretty spot on just as the demo and my modded set sound.

Lots of variables to parse when you want to really get an accurate frame of reference. That's why people eventually find people who hear and listen like you do. It's our intuitive way of parsing lots of potentially frivolous data.