Same here. When I want to get into recovery from bootloader it just sticks at the Google logo. At first I thought my CWM might be broken but via an app or "adb reboot recovery" recovery just starts fine.I'm not sure if it was mentioned in this thread (too lazy to read more than 4 pages) but most people will be unable to access recovery on the 7 via the Vol - + PWR buttons using either TWRP or CWM. This appears to be specific to the 7. Yes, there are multiple apps you can download that will allow you to boot into recovery with no issue. The problem is when you bork your OS and you need to get into recovery using the buttons.
The work around is to plug your 7 into your PC. When you do this, you should be able to get into recovery by using the buttons. I tested this multiple times with both TWRP and CWM and it worked every time. Not sure if you want to add this to the FAQ's for the 7.
However when the tablet is plugged into the PC while in bootloader, there is no problem with starting recovery.