Need to change the Doctype on our site

We were facing few issues in ie9 and after our dev team pointed that we need to change the Doctype, we tried it but found there was no way we could change it in lithium. Then I came accross this http://lithosphere.lithium.com/t5/customer-ideas/Ability-to-Change-DOCTYPE/idi-p/58198

So, we need to open a support case for this? and does getting it changed really affect other areas on our forums?

Thanks