Planning a trip to Borneo

I have been to the "area" many times but never Borneo. I am really amped this summer because I have time to make it to Borneo as well as some other areas in Asia that have great wildlife (Java, Sumatra and Lombok ect..)

Anyone have any advise on Borneo?

I am thinking of getting a 100-400 instead of my 400 5.6.

Thanks

Congratulations on your decision to visit Borneo.
Traveled to Indonesian Borneo 3 years ago and went through Escapes Unlimited, who arranged a guide, boat and cook at a very reasonable cost. We spent considerable time at Camp Leakey where Birute Galdicas a contemporary of Diane Fossey and Jane Goodall has a rehabilitation center for Orangutans.
The 100 to 400 is a good choice as the canopy is quite heavy and there is ample opportunity to get very close to the Orangs.
A magical experience awaits you.