The Newgrange is an underused concept frankly.
It is large enough for 1G grav decks and that is a massive advantage. I envisage colony ships built to similar specifications, go easy on the engines, in fact it need not have more engine power than a Scout class jumpship 0.1G is fast enough, and you can make in system jumps.
The central manufacturing space could be used to store an ore processor and smelter, several internal mining dropships and shuttles and a fabrication unit large enough to make hab dome components.
The vessel could be sent with combat dropship escort to the fringe of known space carrying colonists in comfort, then build a working spaceport and dome city once you get there. After five years the new colony is cut loose and the colony ship returns to the Hegemony/Star League for a new match of colonists.
This way you arent making a ring of slums and backwater worlds but an expansion effort that establishes an infrastructure as it goes along. I could see the Inner Sphere colonised this way. Perhaps these ships existed, then were no longer needed as they had colonised as far out as was practical from Terra and the core.
To me, this would be putting a KF core in one location for far too long (5 years?!?!). I'd want to use it as a
giant freighter with maybe a few Dropships on its exterior. The interior would be equipment for a machine shop equipment, components for a space station, aso, that would be assembled and used on-site to support the colony. To me the colony process would be:
(after making sure there are no dangerous comets/asteroids, plus the planet is safe to live on)
1) Freighter arrives with Dropship with internal Repair Yard, ~1/3 of the pre-made giant space station, and sufficient supplies/personnel to run the Dropship/Repair Yard
2) Freighter returns to base, and the Dropship/Repair Yard begins assembling the first ~900 ktons of station
3) Freighter returns with another 900 ktons of station, and a large number of science personnel/equipment to survey the planet selected. It then takes orders for what the Dropship wants on its next trip
4) Freighter returns to base, loads up another 700 kton of station, along with a lot more materials that the Dropship and science crew will want.
5) Freighter returns and delivers the last components of the station, plus offloading the last bits of supplies.
6) Freighter returns to base for colony materials and the first colonists
7) Freighter makes final trip to colony system, dropping off colony supplies and colonists to new station in orbit. Dropship with Repair Yard re-attaches to Freighter, and it returns to the base system to help set up a second colony. The first colony can now be serviced by standard Jumpships and Dropships, using the space station as the transshipping location.
Instead of the Freighter staying in one location (for 5 years) to perform the manufacturing, it would be delivering components back and forth to the space station, and the space station would be assembling the components into whatever the colony needs. Even assuming it takes a year for the first colony to be set up, it means that the compact core freighter can set up 5 colonies in the same time as the NewGrange machine shop can set up one colony. (It will be more expensive since the material has to be delivered to every colony, but it also means that the freighter can do more work jumping back and forth compared to sitting in one location, and the space station can handle all of the initial industrial needs)