The answer is it depends on the existing traffic coming to your desktop website now, as if its significant (We would need to look at your Google Analytics account) then there is every chance you would get a real benefit in sales and leads from providing a great user experience, which was not the case previously.
There is no denying the amazing growth of the demand from consumers and businesses who are only searching on a smartphone. There are many Google, Forrester and Nielsen statistics that will confirm this.
Therefore if you don`t have existing significant traffic then it is extremely worthwhile investing in marketing the customised dedicated mobile website with Google Adwords for example.
This assumes you have prepared the mobile website first to maximise your chances of success.
Watch the video below for more information on how to grow your sales and leads using customised mobile websites.