I just read the review of BE-10 from the Taiwanese magazine from a few years back. The reviewer did mention that by adding the lead shots, it helped tighten up the mid-bass which he thought was kind of loose in his early listening sessions.
By the way, JPS cables just announced that they have provided internal wiring and crossover upgrades to the BE-10. The new version will be called BE-10 Examplar. But they will also be providing the kit to retrofit existing ones. The cost will be around $6k (US). I forgot to ask whether that is available for the BE-20.
The USHER room was playing both speakers side-by-side. Both sets were hooked up to two completely different systems, one analog and one digital. One was clearly more transparent than the other. But I am not sure how much of the difference can really be attributed to the "upgrade".