Smartpak does have great customer service and have never had problems with them as far as supplements goes... I did have an issue with my custom mugs. :o(
I have my 15 arab gelding on smartflex senior. I would prefer it came in a pellet but oh well. If the supplement your thinking of is more than $40 I would go with injectible adequan.. It's FDA approved and regulated as supplements really are not. It's also way more convenient.