I'm using the EML Mesh Plate 300b tubes in my Balancing Act. They seem well worth the added price over for the EH 300b.
The price for a quad of EML 45's is $1,342 with shipping from tubesUSA. If there is a better price out there, I'd love to get a PM about it!
(EML had a short run of the Globe design but sold out and there are none scheduled for the future. There are globe type 45s that come up on eBay once in a while.)