But since you raised it, why buy when you can trade in? It is not a platinum week, so wouldnt it be an easy trade?
It might be an easy trade depending on the particular week - the highest-demand Gold weeks that bump up against the Memorial Day and Labor Day holidays might not be so easy, the others would be easier. The biggest reason to not rely on exchanging in, though, IMO, is if the view is important to you. (I'd guess it is for the OP, seeing as how s/he's considering an oceanfront unit.)
At least three of the Hilton Head oceanfront resorts (don't know anything about the fourth, Monarch) use the Priority Placement System that favors first owners using their own weeks and then owners exchanging back in, followed by rental/preview guests and other exchangers. At Barony and SurfWatch an exchanger is much more likely to be bumped into a gardenview unit than given the oceanside, oceanfront (Barony) or oceanvista (SW) unit that's attached to an II confirmation; I'm not sure of GO's system between the oceanfront and oceanside units there.
1st Class, I have Gold Barony and SW ocean-front/vista weeks. The other thing about the placement system at both of these resorts is that owners using their own weeks will be rotated among the units if owner occupancy is high and a lot of requests have been made. So, one year you could be placed in a high-floor "best available" oceanfront/vista unit while the next you could be rotated to a low-floor "worst available" oceanfront/vista unit. In my experience both resorts try to follow that policy and I like it, think it's fair for everyone. I've read on TUG that GO has a similar policy. The ocean/beach view is really important to us and at both resorts, we've been happy in each of the 2nd, 3rd, 4th and 5th floor units that they've placed us.
As far as the exchange value of Barony or SW Gold in II, we've done pretty good but really don't exchange out often. This year for the first time in four or five, II is offering bonus AC's for depositing these weeks. I don't know what that means other than I wondered why they stopped offering them back when they did, and it's nice to see them again.
{eta} Sheeesh, I forgot the one point that I wanted to make here. Doh! OP, if you're thinking that you'd be using this week most often as the last Gold week in May before Plat season begins, I can tell you that it's a very difficult week to book using the 12-mos window even if you're on the computer and ready to go at 9AM sharp. I even have difficulties booking that week with the first in Plat season using the 13-mos window; most years I book some combination of three weeks - Gold/Gold/Plat - using the 13-mos window and then cancel later the first week, all to get the Gold/Plat weeks that straddle Memorial Day. I have no idea if something similar happens with the Plat/Gold Labor Day weeks or with any other Gold weeks, but just thought I'd mention the difficulty with that last-Gold-before-Plat May week. It's something to think about.