Is this any help to you?

A Post in FFF (UK site) - by Grommit who has brought the St. Croix range in again to the UK.

"The Imperial is a fast actioned rod wheras the Avid is a moderate/fast rod. The main difference between them, as with any different range of rods from the same manufacturer, is the quality of the blank and fittings used.

In all honesty, I wouldn't have any hesitation in recommending either range as I was impressed with all of the St Croix rods when I first saw them. From what I can gather, the Imperial was actually relaunched as there was an outcry when it was discontinued and going off the number of enquiries we are getting about them, they will remain a very popular rod."

I think that when you get down into the shorter rods and lighter weight lines that a fast action is not really that necessary as you want more 'feel' to your casting.

TLs