I wouldn't have any reservations using the 6.5 with the LRX. I have a 243 that shoots the 80 gr TTSX at 3415 fps that I'd take to the mountains in a heart beat. I have gotten over 26" of penetration at 100 yards when shooting milk jugs filled with water.
I recently purchased a 300 WSM and my gunsmith says I should look at the 165/168 gr bullets. Therefore, the 150 TTSX up to the 168 TSX will be the first I look at. I think your rifle is already telling you that it likely likes the lighter bullet weights.
I have zero issues with the mono metals loosing their petals either. I recently collected my first two 180 gr TSX bullets out of my 300 Win Mag at 3100 fps.
The first was a common reedbuck at roughly 100 yards shot middle of his back, splitting him in two while traveling down the spine coming to rest against the hide on his neck. The bullet lost all four of the petals and he dropped like a rock as imagined.
The second was a blesbok at 326 yards shot hard quartering towards, hit on point of shoulder, found against the hide after exiting his right rear hindquarter. That bullet travelled roughly four foot completely thru the animal and almost exited. The bullet only had one petal left.
Take the 6.5 and don't look back if you can't find a load for the 300 WSM.
Good luck!
