As a member of the first classes of managers to go through Dell Inc.'s new Leadership Edge program, David Marmonti spent 10 days last September in Austin networking with 17 other fast-track executives, including three days of strategy talks with Chairman Michael S. Dell and CEO Kevin B. Rollins. Like many of the hypergrowth companies that shot up so quickly during the tech revolution, Dell had long relied on sheer momentum to keep managers like Marmonti challenged and the company humming. As it went from startup to powerhouse at lightning speed, Dell could ignore the niceties of human resources development. People were dying to work at such a dynamic company. Stock options were making millionaires of mid-level managers. But as Dell, now with $49 billion in sales, charges toward its $80 billion goal, growth is getting harder -- and more of it will come far from its Austin (Tex.) roots.