I've googled if VIP increases homun exp and DrAzzy has replied in forum threads that it doesn't.
However, other people have told me different. I got VIP to try it out, and have noticed a reasonable increase in gain of exp for my homun.
eg. I was lvling a vanilmirth base homun with vip and amistr base without vip. Vanilmirth base was outlvling by around 2.5x until I got vip and now it's only outlvling by 1.5x?