Not clear on what the issue is your dealer is referring to. The two control arms? do not touch each other with plenty of space between them to clearly operate either with no interference. I had never thought of it being cumbersome or otherwise, as they are distinctly two different controls. Just turning 12 years of operation with no issues.
Maybe seasick I was aa little to simplistic with my answer to Joes question, but it is certainly is doable, as with most mods, just think it through and take your time. The single control once removed will give you a good idea on the bits and pieces in the dual control before you reassemble.