I am from Jiangsu China, I've listened to Beijing people say erhua, '一点点儿'，'一点儿点儿' are all normal to say. You can decide which to say based on your preference.
And, you can totally say '一点儿', or '一点点' to express 'a little'. People get that, it's normal and they all have the same meaning. [Young people sometimes also say '一丢丢(diū)' to express 'a little', sometimes girls think that's cute]
Besides Beijing, from cities like Tianjin and Kaifeng are people who say erhua as well. You can talk with or without erhua, that's totally fine. And for people who are not from above cities, they sometimes also say erhua and that's not abnormal.
No matter what you say, people get that and it won't be too weird if you say that very slowly and stress each and every character. From my view, it's only a preference thing.
I just asked my friend from Beijing, he said that you are right, mostly commonly people say '一点儿' or '一点点'. And mostly the erhua is used by '老北京'(older generation in Beijing).