I've used the Ivomec products for years, on cattle, sheep, goats, dogs, pigs, and now poultry. I just stay with what works, and is fairly easy to administer. One product I will NEVER use again is Valbazen (sp?). Had some severe deformities when used on goats, and have never used it since.
I hear ya on sticking with what works! I can't help but get curious about what works for others or why people prefer one over another kind of deal.