Answer
The honest answer depends on remaining IBM support runway, budget, and how critical the workload is. New hardware carries the longest support and warranty window but at the highest price. Refurbished hardware can deliver most of the same capacity at a meaningfully lower price, provided the seller tests and warranties the unit properly.
Buyers should compare total cost of ownership over the realistic hardware lifespan, not just sticker price, and should always confirm the refurbished seller's testing process before assuming price alone makes the decision.