Allright, I've originally put Gear 2 at a 10x multiplier, making his power level in Enies Lobby go from 850 to 8,500. Rob Lucci's base Power Level is 4,000, meaning that the Hybrid Forms multiplier would have to be ATLEAST 2.125, (4,000x2.125 is 8,500, and I'd say that Lucci and Gear 2 Luffy would be pretty evenly matched. But I found out recently that a Leopard is 7x stronger than a human. Meaning that Lucci wouldn't be a 2.125 or so multiplier, but a 7x. What is 4,000x7? 28,000, not 8,500 (obviously).
Learning this, Gear 2 was definitely not a 10x multiplier, but around 35 (I decided to bring Luffy to 750 because of Blueno). 750x35 equals 26,600.
If you think this is a crazy multiplier, do NOT ask me what I put Gear 5 as...