I fitted an over sized 602030 LiPO battery to my GW60 watch mid last week. Tested ok. 8.5 hrs uptime (in GPS logging mode).

tonyk contacted me via PM last November, asking me about LiPO battery technology. He mentioned the 602030 may be able to fit into the GW60 unit with the springs removed (Nb/ springs power the Piezo speaker). I though that was a great idea, so I ordered the battery.
After testing battery (due to the logistical issues mentioned above), I fitted it to my GW60. I scrapped off the piezo speaker, and desoldered the springs that powered the piezo speaker (the ground spring was very difficult to desolder). I then had to cut away more of the cover (using a dremel) to make battery fit. It's a tight squeeze, but I got it in there.
I cleaned up the mating surfaces with IPA, and cleaned the gasket with some damp tissue, and then lubed gasket with silicon grease.
Job done. Ready for George