Here are some results for my Lite-On LTR48125W VS08 on a CD-RW 80min/700MB 10x disc.
For standard UDF 1.50 formatting, physical format takes about 8 min and logical format takes about 3 min (i.e., 11 min in total). In contrast, initial CD-MRW formatting takes about 30 sec (the disc is usable at this stage), whereas background formatting takes about 9 min (without influencing copy speeds); in both stages, ejecting the disc takes several seconds. As for space, InCD reports 50KB used, 572MB free for UDF 1.50, whereas CD-MRW has 539MB free.
The copying and reading speeds seem to be comparable for both formats.
UDF 1.50 discs can be read in CD-ROM or DVD-ROM drives under WinXP SP1 natively (without installing EasyWriteReader).
CD-MRW is claimed to be more reliable because defect management is done via hardware; however, apparently none of the popular burners have passed the EasyWrite test.
I have been using both formats with quite cheap media, without significant problems so far. Still, packet writing to CD-RW discs is not reliable enough for primary backups.