I currently shoot with a Bowtech Mighty Mite,70 pounds 30in draw length.
The reason for the post is I want to change to Carbon Express arrows and would like to hear of any positive/negative views and what woould be the correct shaft to use. Some feedback regarding vanes would be great too!

450 spine, it looks like to me. They have an online shaft selection guide. I made some assumptions about your release, cam, 125gr points and inserts, etc. But you can go there and take a look and fine tune it.

I like the carbon express arrows, though I have trouble keeping them fletched.

I have been hunting with Carbon Express Maxima Hunter 350 arrows the last 3 years.

They are very accurate and tough.

A 30 inch arrow with 125gr broad head give me 450gr arrow.

I prefer hunting with 4 inch vanes.

I use the same arrow , vanes and weight, broadhead weight as Gerhard,,,,I shoot a Mathews Switchback at 70 lbs,,,I have never had an "arrow" failure with it and over 20 african plainsgame including the big stuff, Eland and Giraffe make me comfortable with the set up not counting all the pigs and deer shot with it here in the states.