ENT's are all specialists. Having adenoids removed is a very minor operation, and baby/toddler/child barely notices it. Tonsils are a bigger issue and are actually quite painful afterwards.
My son had serious ENT problems, has had grommets (3 sets) adenoides removed, tonsils, ear drum graft, and various other issues.
20 months is really young. I am do not know your child and do not know the circumstances, but I would be cautious about whipping about anything and putting my child under any anaesthetic if there is an option to avoid it.
You also need to consider the environment - if your child is in a creche/daycare etc, odds are he is being exposed to numerous infections and is being reinfected almost daily. This may be something to look at.
Just be sure removing adenoids/tonsils are at that point where they are absolutely necessary before embarking on it.
It is winter now, so kids are more likely to be in a situation where they pass infection on - as said, I am not a doctor, do not know the severity of your son's condition - but personally I would explore other options (anti-biotics, changing the enviroment, etc) until I am sure that removing them is the ONLY option remaining.