What factors should be considered when deciding between the Merida Silex 6000 and Van Dessel ADD, particularly in terms of ride comfort, durability, and versatility, for a rider who plans to use the bike for both gravel racing and commuting on varied terrain? How do the design philosophies and geometries of these two bikes influence their performance in different riding conditions, such as smooth singletrack, rough gravel roads, and paved bike paths? What are the key differences in their component specs and how do these impact their overall value and ride quality? Are there any notable differences in their tire clearance, brake systems, and gearing options that could sway the decision in favor of one bike over the other? How do the Merida Silex 6000 and Van Dessel ADD compare in terms of weight, handling, and responsiveness, and which bike is better suited for riders who prioritize speed and agility versus those who value comfort and stability?