Hey everyone. I have a 17hand Trahkner (Rhett) with 1/4th of Percheron that weighs around 1800lbs. Needless to say my big boy is h e a v y on his forehand. He pulls down on me, lengthening his stride, getting very fast and very strung out. I am 5'6" at 120lbs and I can NOT hold his big boy up and rock him back with out some bit help. I bought him riding in a O ring snaffle (he was a dressage horse) and when I started jumping him(transitioned to hunters) I quickly moved him to a D ring with a french connector (i think) for better steering, then finally to a full cheek with a slow twist. He was still too heavy... so then I tried a fullcheek waterford, giving me only a very small change, then I went to fast twist full cheek and he is still like holding a cinderblock up at the end of my reigns as we freight train our way around the ring. I am ready for a big change. I have been looking into the two bits listed at the subject.
The Broken Segunda: 
http://www.doversaddlery.com/product.asp?pn=LC-01737&tid=shopzSALE&CATALOG_CODE=1X844&EID=X1844001&zmam=1460880&zmas=1&zmac=45&zmap=LC-01737&bhcd2=1278818306 or the Myler Low Port: 
http://www.doversaddlery.com/product.asp?pn=X1-01104&tid=froogle&CATALOG_CODE=1X814&EID=X1814001&zmam=1460880&zmas=1&zmac=49&zmap=X1-01104 I tested out a Segunda during my hack today and it worked wonders; however, I could definitely tell it might be very harsh (just as most of my research on the bit said) and the comfort and care of my horse always comes before our performance so any feedback from former users, opinions from people looking at pictures of the bits, anything!
Thanks so much, MariMarie & Rhett
xoxox