I have both the 6x8 and the 4.5x7 Excelerator. I like the SEF OK, but hate, hate, HATE the open coil design. It catches on every bit of stubble, most rocks and some low cactus. What a ginormous pain in the butt in the desert ghost towns where I typically hunt! The 4.5x7 has none of those issues. I have hunted smoother more even areas with the SEF and it worked fine, but finally decided to just leave the 4.5x7 on since it seems to work as well or better - in all environments! If I could find a way to close up the open design of the SEF, I MIGHT learn to love it, but as it is, I think most of those who rave about the SEF simply have not experienced the joy of using the 4.5x7.
In fact, I will make this offer - Buy a 4.5x7 new or in excellent condition. Take good care of it and use it for three months. If you don't love it after that time, I will trade you my excellent condition, lightly used, purchased new, 6X8 and I will keep the 4.5x7 as a backup!