Dark roast is not dead. Actually, most of the population of the USA are still...
Will upsizing your roasting machine result in downsizing your quality performance? No, not necessarily.
Important remedies to prevent a negative impact on coffee quality as a result of your pending expansion:
Develop a thorough technical understanding of your coffee roasting system; analyze how your current machine actually works and how your (possible) new roasting system functions.
Keep records of profiles and understand what the important parameters are for flavor notes of your coffees.
Experiment with different roasting times and colors to understand the flavor dynamics of your coffee.
Equip your new roasting system with effective gauges for measuring your roasting performance.
Apply blind cupping protocols to compare results. Possibly, involve a consumer focus panel to periodically assess the flavor profiles of your coffees.