One thing to consider, IM ratings on rods can be misleading. Rod manufactures use this rating as a marketing tool. IM8 is better or more sensitive than an IM6 right? What you need to look and what can be almost impossible to determine is the grade of the graphite used or if the blank is carbon. Then you need to compare components, handles, reel seats, warranties and where the rod was manufactured.
Quality components like the components St.Croix uses can increase the price of the rod very quickly. As well as the grade of the blank. What I think the St.Croix rep was trying to explain was that the Premier series is a lower end grade blank which it is to St.Croix standards compared to the Avid line of blanks. But this also means the Premier blank has much more quality over the mass produced over seas type blanks. Ive used and owned Premiers for years. I remember when they were $40 new. I still use them and have never had a problem with them and they go through alot of abuse.