|Bring one of these for the rainy season|
1. Few people on the mountain
2. Prices to climb the mountain should be lower
1. Lots of mud. You NEED trekking poles
2. Prepare to be cold and wet for many days
The one other advantage of rainy season and disadvantage of the dry season is that you never know what the weather is going to be. In the heart of April or May, it can be dry for weeks. In the middle of the best climbing season, it can rain, rain, and rain some more.
Take your chance and see what happens.