Forum Academy Marketplace Showcase Pricing Features

Integrating 2 themes into 1 app

HI all, I am newbie. Looking to build b2b, b2c, c2b service, product and project based marketplace app. How difficult it would be to integrate 2 themes in to 1 app for example Gigster and Marketo (both offered by Zeroqode)? Any helpful direction / suggestion would be great for my decision making. Wandering whether if starting with one theme and customize / develop to my need would be a better option. Is there any tutorial for this subject? Thanks.