Cost tolerance (and feasibility) is of course a personal decision. That said, I advise people to take into account the tremendous potential mileage-earning benefits of a well-crafted business class RTW. In many cases, and depending on your FF program, you can leverage sufficient miles from the RTW to "pay" for a considerable amount of future travel.

As an example, an AA Plat member (easy to achieve using the Challenge) on a 60K mile RTW can book well over 130K "spendable" miles. An AA OW130C Oneworld award allows up to 20K "net" miles in business-class travel ("net" meaning only miles between stopovers are counted.) YYZ-LHR-SIN-HKG-YYZ is 19,700 miles - in other words, a second J-class RTW funded from one paid one. And so on.

An L class RTW will also earn miles, but not nearly as many, thereby reducing the leverage capability. But the cost spread between a LONE4 ex-UK and a DONE4 ex- somewhere else may be the equivalent of a second LONE4, so it's an individual call.