Of course it's 'fair.' Provided one's use-case isn't sensitive to the difference in thickness, then saying that difference makes them incomparable is like saying you can't compare them cause they're not the same color.yeah as above posts have stated not really "fair" to compare a 25 vs a 30.
They were made once, long ago. The Feser Triebwerk 120mm fans were 120mm Square x 55mm thick, and were used to rival the early GTs used in early PC water-cooling builds. In server computing, Delta and San Ace have made 120mm Square x 76mm thick fans; basically 2 38mm fans combined into one unit that use a counter-rotating setup to really straighten the flow and push the air back further than a 120mm Square x 38mm thick fan with fixed counter-flow vanes can.Though I agree that there are many applications where the extra height doesn't matter... Now I'm just waiting for someone to make a monster 50mm version