I've had one, killed a lot of trophy deer, etc. with and will give you reasons a fixed 6 is good.
I went to a higher power from 4 to 6 put on a Remington 6 mm Carbine '59. I grew up guiding, have guided close to 100 whitetail clients and killed over 100 myself and some mulies, point, I was looking to add excitement to my shooting, since I kinda had down most shots to 450 with rest on still game. Now it was about shooting running game. Any there is a subconscious perspective that gets thrown off if your adjust power and your are digest the fine art of consistenly hitting runnning deer, much like putting arrow on top of arrow by a feeling. I later moved up to 8X although the adjustment to the 8 was longer and harder than I thought, a running deer under 150 yards was dead. Then I went to pistol hunting then bowhunting. I learned the HI POWER trick from two German men that owned a liquor store set off the hi way and they would site in the liquor store, with bolts out of the rifles and swing on passing cars hubcaps, distance from 75-200 yards. One shot a .270 model 64 and the other some performance caliber in a Weatherby. One of these men shot a 10X, the other a 12X, they pulled up to our huntinig camp on the James River at noon, came in had lunch w/us and went hunting in the heat of the day, talking an 80 degree November Texas day. They get of opposing sides of these steep, deep, scrub, cedar and live oak line draws or gourges, They had their pace and hand signals down and would signal each other when it was time to throw a rock into the small canyon, wouldn't be long till they'd bust a buck out and he'd try to make it up the way, but never did.
Tony Dukes...........TEXAS