A properly soldered ring with the right treatment will not have a seam. On the other hand, castings can easily end up with imperfections and porosity, especially in the hands of an amateur with limited equipment.
When you talk about symbolism, it really doesn't matter if you can see the solder seam. Yes, of course a good jeweler doesn't leave visible seams. (Heck, a mediocre one doesn't either)
But the message of a cast ring is "it never had a beginning or an end. It's forever"
And if you read OPs post, they care about symbolism.
