Actually exept for starburst (and maybe flare?) DA 12-24 performs better than the DA 15.
I personally find that when I shoot primes, I become much more disciplined in composing, looking at subject, and observing how the light works on the subject. That alone make me prefer primes whenever I can afford to use it.
Also like I said previously, shooting strapless with DA 40 and a grip. Camera weight is distributed top to bottom instead of front to back. I just find it very ergonomic / comfortable. It's similar to enjoying a drive in the highway with one hand as opposed to two hands (dangerous I know, same as carrying a $1000 equipment with no strap)
You're right though that in regards to performance, modern zoom lenses are no worse than DA limiteds (except maybe regarding flare, most DA lims are invincible to flare)
FA limited is another story though as their rendering in the right light is quite special imo
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