Among the dozens of providers of tablet-based POS systems, Revel Systems stands out for it distribution strategy — selling directly to small and midsized businesses. Also notable is that Welsh, Carson, Anderson & Stowe (WCAS), one of the most knowledgeable investors in payment systems, is a big backer. It recently committed $100 million in Series C funding to Revel, including $25 million in the form of an equity line. Revel Systems focuses on quick-service and full-service restaurants, small retailers, grocery stores, and franchise outlets. Its commerce platform features complete fron...