It has been done but HH for summer is very difficult. DVC HH will be far easier to get if you book day by day at 7 months out. If you need a 2 BR for a week, put in a request now as it'll be cheaper (270 pts) plus, IMO, two of the 3 resorts for Marriott are overall superior to the DVC HH resort based mostly on location, namely beachfront. When DVC adds the newest Marriott resort (surfwatch) add it to the list above as in the group to select. The order of preference for me would be Grande Ocean, Surfwatch (once it's added) then Barony. I think GO is in a much better location overall plus it only has ocean side and ocean front units. Barony Beach and SW both have garden view units with SW having better ones than BB and as an exchanger this is likely what you will get. If one did a direct exchange that order might change as I think the BB ocean side and OF units are likely superior in location to Surfwatch.
DVC is a great resort, it's the location that is not as good from my standpoint. Monarch isn't an option since it's not on the list. The other resort is Harbour Club which is not worthy of a DVC trade unless a very peak week IMO. Anything starting week 34 or after will be easier than the summer. That's usually the last full week in August. The later you go the easier other than the holiday weeks of Thanksgiving, Xmas and NY. Planning a full year out I'd think your chances of success are VERY high. Just remember you can only get 2 BR units for a full week. That difference alone is a deal breaker for some and not important for others.
For an ongoing search you should have no problem for that time. I just checked the list and they have recently added surfwatch which is really fast the way DVC normally adds new resorts and good for possible DVC exchangers. SW is also the only one that has 3 BR units of the Marriott's. Here are the DVC seasons for GO for a couple of years ago, I doubt they've changed and would expect all the Marriott's on the list to be the same from a DVC standpoint.
