This paper assesses the techno-economic prospects of different wideband transmission configurations to scale capacity in optical transport networks. Detailed optical performance estimation and a simulated network loading according to a given traffic profile and growth rate are executed for the different transmission configurations to realise a meaningful techno-economic comparison. Moreover, simplified cost modelling is utilized where some contributors are assigned a single relative cost. In contrast, the remaining cost contributors, for which there is a higher uncertainty (e.g., immature technology) or variability (e.g., scenario dependency), are the subject of parametric analysis. The simulation results over a reference transport network allow us to gain insight into the specific conditions where each wideband transmission configuration is more cost-effective than the remaining ones.