Crowded? I highly doubt that it would affect performance in any measurable way. As for interruptions, it has gone down before, but I probably wouldn't be able to keep a better uptime personally without investing some significant cash.
Peers not finding each other is usually resolved adding a TURN ICE server, which is generally speaking a paid service, separate from a signaling server. Hosting your own signaling server would be no different as far as connectivity goes for this type of issue.
Before you worry about signaling, you should make your game first (try the free service)... There will be plenty of time to figure out if you need your own down the line. The same amount of work is involved to set up your own now or later, so better to spend your money and effort when you actually need it rather than do it ahead of time when you might not even need it at all.