Update away. There are many other improvements which you will use every day. Take a look at the section on what is new in 13.
TW2 is great. It's not just about the BIMserver, but how you work in TW2 is sooo much faster. Set it up and get to know it.
What's that boy scout motto 'Be Prepared'
Seriously, go ahead and update.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"