Those Exiles didn't last for long! You're right that they look equal spec-wise, but that is all I got. I have zero experience with Sundown. Don't forget you have a WS retailer in your backyard that might give you a deal!
If I knew I wouldn't have my balls removed for my person I would sell you my SYN4 so I could upgrade to the SD4, but I like my balls... and being married!