I would call it a very loud guitar. That’s my opinion, of course, and everyone has a different set of ears. I have a friend with a refinished late-1939 D-18, and my Vintage Artist is every bit as loud as his guitar. I’m not familiar enough with the sound of a Collings D1A to be much help in that regard. I’m sure there are some very knowledgeable players on this forum who could weigh in on that if you put the question out there. The few Collings dreadnoughts that I’ve played seemed to be quite bright and forward sounding. I’ve read more than one post from other players who feel that, as you say, the Vintage Artist is a sweeter sounding, more balanced guitar. But that’s secondhand information, so please take it for what it’s worth.
A Footnote: an unforeseen work situation has called me out of town for a few weeks, and I was unable to bring the guitar with me. As a result, the soonest I would be able to ship it would be mid-July. I thought of pulling the ad temporarily, but since not everyone is in a hurry, I thought I’d leave it up–with this footnote–and try to respond to any inquiries. I sincerely regret the inconvenience, and realize that the time factor could be a deal-breaker. Some things are simply beyond our control. I don’t know how to post photos on this forum, but I do have a number of pics of the guitar on my computer that I could attach to an email.