Are you affiliated with EasyMLS? I can't say whether it is worth a try or not.
When I evaluated whether to take on building something, my assessment was that a lot of people are trying to inject themselves into high-end transactions to get a piece of them. I think a good broker adds some value to the transaction, but for the most part, they just siphon money out without really adding much net benefit. I just didn't want to participate in creating another middle man.
I get the value proposition of such a service and, at face value, it seems like a good idea. In reality, they mostly just generate noise. True, you can post more widely, but then so can everyone else. I am not sure the seller benefits at all. I expect the pros and cons are about a wash.
Now, if you are selling something very specific, for which the market is very limited, casting a wide net might be beneficial to the seller. But, in those cases I would expect that brokers have existing ways to track down something specific for an interested buyer. Any current/former brokers have insight into that process? This was all explained to me years ago, but I don't recall. And, things change.