I've always struggled with any test in a guitar shop so I've always bought on recommendation/research. I bought most of my valve amps like this and if I'd tried them probably not bought them because it took me time to get used to the sound.
I think this is probably even more true for digital equipment because dialling in sounds can take time ( ironically the KPA could be the exception to this as I'd argue its been the most plug and play compared to other units but even then we know how different profiles can sound).
What I'm really saying is I don;t have as much faith in my ears as you :)...can you come with me when I next buy an amp ha!
Even with the Kemper approach, it was a slow process finding the ideal profiles and sound for live use. Having a Helix too, this just transfers the work to finding the right IR instead.
If I buy a modeller or amplifier, I always give it at least 3 months to expect the best from that gear.