We just bought into CCV last month and we bought a Guaranteed Week for Week 48, which is usually the first week of December (it sometimes starts at the end of November). Given all of these difficulties I've read about, I am very glad we chose to do that. Having to use an additional 11 points seems well worth not having to worry and knowing that we have the week booked (first time won't be until 2020, however). When we purchased, Week 49 was still available - not sure about other weeks.
Based on what I've read from others dealing with sales guides on Guaranteed Weeks, I would highly recommend the guide who helped us - I can give you his info (Ron Brumbaugh). He was not that familiar with GWs, but he was really good about calling higher up the chain and getting the correct info and getting back to us. Also as he got more info, he seemed to change his view on it a bit and saw the advantages (he initially just knew that it cost more). He's been with them for 28 years but was not afraid to admit that he didn't know an answer because it's just simply something that does not come up for them that often. I've read others just getting bad information from sales guides on GWs or being simply told they have to pay too much extra and it's not worth it. They are also currently selling December Use Years. When asking about how that would work with the overlap sometimes, Ron also got approval to have us switched to an October UY to make everything simpler (called us unsolicited days later to suggest we switch it because it would avoid any complications with the Week sometimes spanning two different UYs).
That week (Week 48) would be 107 points. We purchased 118 points and it will be 118 to book that week for us. However, if we choose to opt out and use the points elsewhere, we have all 118 to use. The extra 11 points seems well worth it to guarantee that the week is available to us.