Eb1;
I'm in agreement with you all the way. I've used the 100gr Rem. Corlokts and they do shoot well. A bit slower to expand than a Nosler Partition, and in my experience, penetrate just as well, or better. My wife killed her first deer with my .257Roberts with a 100gr Corlokt handload @ 3,100fps from my rifle. Perfect performance with a heart/lung shot. Ran 75yds and dropped. Bullet exited leaving a 3" exit wound.
However, there's just no beating the accuracy of the Sierra bullets. I too really like the flat-base ProHunter's. However, not as accurate but just as effective on game and holding together as well, is the Hornady 100gr flat-base Interlok. I've shot more game with these from both the .257Robt as well as .257WbyMag, and the few I've recovered have held together marvelously. One from the .257wby @ 3,500fps m/v recovered from a doe shot through the chest at ~90yds held together and weighed 63.5gr. Perfect mushroom. Oddly enough, they will penetrate better when fired from the .257Robt @ 3,000fps. Never recovered one fired from the Roberts... Except a 117gr BTSpt Interlock @ 2,800fps from a 275lb buck I shot at ~270yds and bullet traversed the torso and was lodged under the hide on the far shoulder. That bullet weights 105gr and a perfect mushroom that reversed (swapped ends, like a badmitten birdy) due to the imbalance of the mushroomed shape and was base first against the skin. Deer was a bang-flop even though no spine or CNS was hit. Very suprising as he was chasing a doe at the time.
There is only one thing wrong with a Marlin XLS in .25/06..... The 22" bbl.
Thats the only reason I don't already own one in .270wcf...... But, if I run across a used one at a Pawn-shop, I'm sure it'll go home with me!!! (either a .25/06, or .270wcf for that matter....). I had one in .243 (blued steel) and was pleased with it. However, a friend pried it out of me for his son for Christmas '10.....