I appreciate your question but I am probably not the guy to answer it for you since I can only comment on what I have personal experience with. I can tell you about my personal light 338 ultramag rifle though. It is an off the shelf Rem 700 Stainless synthetic with standard weight 26" barrel. I bedded the action, freefloated the barrel, put a good trigger on it and a brake. This rifle with a 3-12 cabelas scope and hard case was $549 new at cabelas a couple weeks ago. I bought mine used a while back. I bought it as a lightweight long range backpack rifle for elk. I haven't weighed it but it is as light as you can go with this cartridge and still have a legitimate long range rifle that will shoot accurately and you can hold comfortable/steady with heavy bullets. It feels about a pound heavier than my Tikka T-3 light which is about 7 1/4 pounds scoped. 338 win mag is the biggest thing available there and is the biggest thing I would shoot in it.
I can tell you that I highly recomend this rifle. I have numerous rifles built on the 700 action that perform well. Most any gunsmith knows the 700 action and with all the available aftermarket parts available if you ever wanted to customize it there would be no problem there. This rifle shoots about anything I put in it well. For a backpack hunt this year where I couldn't carry my heavier long range 338-378 I loaded 225 noslers at 3264 fps. On a simulated hunt where I stalked the target then stopped ranged and fired from a bipod I shot a 4" group at 752 yards with this load. In my opinion I feel I could kill an elk at a 1000 yards with it if I had to and the conditions were right. On a real hunt I shot a very nice old 6x6 bull right through the chest at 740 yards. He staggered maybe 25 yards before falling. Unfortunately I didn't know he was dead and fired two more shots at him through a small opening where I had a good shot at his chest thinking he was standing there instead of lying dead on the steep slope. When I got to him he had three shots right through the chest. I am not familiar with other manufacturers in this chambering but I can tell you this is a good rifle that I have tested and am very pleased with. Again, it is as light as I would go with this size cartridge. Sorry I couldn't be of more help. I will say the 338 ultramag is one of the best long range elk rifles out there.