I had one built on a M98 action in 1983. It has a light contour E.R.Shaw bbl, and a "fancy" grade Bishop classic featherweight stock. Rifle was blued in a deep polish blue and is stunning good looking. It shoots as good as it looks and has taken over 100 whitetail deer, a mule deer, and over 50 prarie dogs in one afternoon. I've hunted black bear with it, but never "connected". The largest animal was a white-tail buck that field dressed over 200lbs, which gave it a near 300lb live weight. That deer was taken at approx. 240yds with a single shot from a 117gr Hornady BtSpt @ 2,870fps m/v. (Over book max load of H4831). Nowdays I use either the 100gr Sierra or Hornady over 45.0gr of IMR4350 for a mild "deer" load thats sub moa, or the 115gr Berger VLD "Hunting" over 45.0gr of IMR4831 for near 3,000fps for "splattering" deer "innerds" at longish ranges....
The only thing I would hesitate to go after with the "lil Bob" is the great bears. (grizzley, brown), simply becaue I have better suited guns. Likewise, if after elk, caribou, or moose, I'd simply use another gun because I have bigger ones more suited.
But, for pronghorn antelope or deer, it doesn't get better than the Roberts. I've also owned a Ruger M77MkII in .257Roberts but I sold it so I could buy a Ruger "Hawkeye" M77MkII in .375Ruger. The .257Ruger wasn't particularily accurate, the .375 is... so it was a good swap. I also have a .257wby Vanguard, and though it's an accurate, flat shooting rifle, it's 3lbs heavier than the "lil Bob", so it doesn't get hunted nearly as much. It's a "bean field" or power-line r-o-w rifle for a shooting house. The "lil Bob" is a tote-it-all day rifle for the steep mountains.... My wife and oldest daughter both took their first deer with the "lil Bob", so it's a reviered member of the family....
I frequently think about building one on a bull-barrel for a varminter. The 75gr and 90gr Sierra Blitz Kings should reach way-way out there and slap vermin..... All the prarie dogs I've shot with the bob were with the excellent 85gr Nosler B.T. It shot flatter than I had been lead to believe by the ballistic charts.... Launch speed was a chrono'd 3,350fps over H414.....
If you get a "bob", you too will be a "believer"....
FWIW; my "bob" gets similar velocities from a 22" bbl as a friends .25/06..... They are very, very close with reloads as there is less than 5% difference in case capacity.... Until the "4831's" came out, the "bob" was the better cartridge, hence coming out in factory form 50yrs before the .25/06 came out.... I still believe it's the "better" .25.....even including the .257wby....