I can't speak to the Newport specifically, but my S2 is a masthead rig and the opposite is true. I have to reef the main as soon as wind speed hits 10 kts, but I can comfortably carry a large genoa at that speed. I hear that's pretty typical for S2s, so there's more to it than masthead vs fractional.
I admittedly posted in haste yesterday because I was at work and didn't have time to give a more complete post. In doing so I assumed he did everything else prior to reefing that should be tried (IMHO) prior to reefing. I will go into more details below.
Disclosure: I am by no means an expert. I have never taken a sailing class (other then at boy scout camp as a kid). What I am saying is just what I have learned through experience and experimentation and what I have read. So again, please correct me if anything I say is wrong or confusing.
When reaching through sailing close hauled, weather helm is typically caused by the power point on your rigging being too far aft. Lee helm is caused by the power point being too far forward (any of us that go out for the lazy evening sail and just roll out the head sail have seen this). Typically the power is too far aft because most of us have a tendency to over sheet our sails.
So when I have weather helm, or excessive heal, the first step I take is checking my sail trim. I start with the head sail and trim until all tell tales are flying correctly. I follow the three rules of head sail trimming for that. Then I let out the main sheet until it starts to get back winded. The traveler is typically over the center of the boat if you have one. My C&C did not but many of my friends' boats do that I sail on frequently. My main halyard, out haul and Cunningham are typically a little loose at this point.
If I still have excessive weather helm (because you do want a small amount of weather helm) or the boat is healing too much, then I flatten out the main by hauling the main halyard, out haul and Cunningham tight. This depowers the main sail by reducing the sail pocket. If you have a back stay adjuster, you can also tighten this to flatten the sails and depower.
If I still have excessive weather helm or heal, I try moving the traveler to leeward and let out sheet until the sail is back winded to the maximum extent possible. This depowers the main by changing the shape of the sail pocket and "spilling" wind.
Now the sails have been trimmed to the best extent possible. If the weather helm continues, now I will start to think about reefing.
On our C&C, before we added the roller furler, we typically used our 100 jib. We also had a storm jib and 150 genny. We never carried the genny and only had the storm jib when heavy winds (over 18-20 kts) were predicted. So our only option was to reef the main typically. I also did not like changing a hank on sail in the conditions that were typical when it came time to reduce sail.
But when we went to the roller furler, we had the 150 genny cut down to fit on the furler, so it was around 135 to 140 genny. With this set up I found that the full genny was typically causing the back wind on the main earlier then it should be happening without the influence from the genny. So I would furl in the head sail to approximately 75-80% of the head sail area. Now I would retrim the mainsail with the sheet and traveler. This typically would cure the weather helm and excessive heal.
If I had to furl the head sail in to less then 40% of the head sail area, then I would think it is time to reef the main.
I am hoping this same approach will work on my new boat, Catalina 310. But I won't know until the spring.
I hope this clears up what I mean by my previous post.