Self-funded health plan at 175 EE — what's the operational reality?

Our broker is recommending a self-funded health plan with aggressive stop-loss. The math on a typical year is compelling but I'm nervous about year-2 if we have a bad claims year.

For people who self-fund at the 150-300 EE range: what's the actual variance you see year-over-year? How do you budget for the swing? And what TPA / network combinations are people running that actually work for this size?