CWA is only beneficial if you want ARP at a resort that has higher maintenance that CWA. For example, CWA is cheaper to own at than Bonnet Creek, so it makes sense to own CWA if you need Bonnet Creek ARP. If you need Myrtle Beach ARP, you're better off owning Towers on the Grove or the cheaper Ocean Boulevard Tower (I forget which one is cheaper). It's very rare that you need ARP anyways and isn't worth the investment.
Personally, if I REALLY needed an ARP week, I'd rent the week off someone with the ARP I need and rent out my own points. It isn't hard at all finding a person with CWA. It's a little more costly that way for the reservation, but at least you aren't contracted into high maintenance fees. I plan on doing that if I feel the need to stay at a Marriott because they rent out at the same cost as owning, but isn't a commitment.
Yes and no. CWA isn't
only benefical if you want ARP at a resort that has higher maintenance than CWA, because CWA doesn't own inventory at all resorts. For instance, CWA owns zero inventory at Midtown 45. If you bought CWA and wanted ARP at Midtown 45 in NYC, you are SOL since CWA literally owns zero inventory at that resort. CWA only owns inventory at around 75 resorts at present. There are many resorts where CWA owns inventory, but it's very much in the minority of the inventory - which may translate into a frustrated CWA owner who can never find availability in the ARP window for a particular resort. That said, you can always go the route you suggested, and rent from a CWS owner if you own CWA, or vice-versa, to get what you want.
Let's look at the actual CWA ownership data for Bonnet Creek:
CWA only owns 27.88% of all available inventory at BC at present. So if you are a BC aficionado and want to book in the ARP window persistently, you are probably better off with deeded ownership given the majority of the inventory is CWS.
Let's look at Myrtle Beach resorts as well:
So, depending on which resort you prefer in MB, the CWA ownership varies widely. Towers on the Grove sits at 47.96% CWA ownership, so it's pretty much a wash between CWS/CWA, so make your choice on which to own. OB in comparison - not much CWA ownership across the board really, so better off with CWS deeded ownership if ARP for OB is important to the OP.
I'm a data hound so I have built a sheet that contains all CWA ownership by pulling the data out of the CWA POS books over time. The screenshots above are from my concatenated data sheet.