Sorry, If I wasn't clear in my attempt to be brief. All metal head tubes need to be reamed after the frame is joined. I use the Paragon head tubes, because they offer the versatility of using various steerer types by changing the headset cups.

There are very few suppliers of integrated head tubes for framebuilders, but Solid Bikes is one that comes to mind. I have seen comments from some builders that the Solid Bikes head tubes are heavy enough that they don't distort from welding and don't require the bearing seats to be cut. In terms of cutting(or cleaning up)the bearing seats, cutters are available for head tube reamers(Park and others) in the various sizes and angles that integrated head tubes use.

Personally, I wouldn't want to spend money on the bearing seat cutter for what seems like very little benefit.