It's not just the pump that determines the performance of a system, it's also the piping. Both the pump and the piping have a flow vs head (pressure) curve. It's where those 2 curves intersect that the system will operate.
Going with a larger ID hose will give you less restriction (i.e. less pressure drop), but at the expense of a more expensive hose and a significantly larger volume of potentially wasted wort. You can run a volume calculation very easily to determine how much.
Also you may want to consider cleaning that hose since it's on the cold side. There's no way you're going to get a brush 25' long, so it'll need to be CIP'd. For CIP to be effective you need high flow rates (several feet per second). The larger the hose, the larger the pump you'll need to get the flows.
In your situation i'd look to use 3/8" tubing to minimize the volume in the tubing and increase the linear speed for CIP, and push it with your pump since you have one. It probably will gravity feed but if you have an horizontal or even inclines areas on the path you may run into trouble trapping bubbles, which will really slow you down.