The puck holder is a great addition to your sjoelbak especially if you intend to use your board on a narrow folding table that doesn't have a convenient place to stack and access the pucks quickly.
An interesting side benefit for less experienced players is that it lets you know at a glance how many pucks you have remaining during any given round with just a quick glance since they are organized in stacks of five. It's also just a cool accessory to have and thus wins some style points with players at all skill levels.
The only drawback is the cost but it's precision custom-built piece that gives you the flexibility to play on any kind of table.