I've tested the battery consumption on my HD2 with radio v2.06.51.07 which is included with the stock Rom v1.61.
I'm here on the Telfort/KPN Dutch network on the 3G/HSDPA band. I'm polling my (3) mailboxes every 20 minutes, with a schedule started on 7AM and stops on 10PM. 3G connections are terminated after 1 minute of idling (via the reg tweak). I have non Sense features updating automatically.
7:40 - 100% - HD2 pulled from the charger
9:40 - 96% - Manualy updated weather through Sense
10:40 - 92% - 5min phone call and reading a pocketword doc.
11:40 - 89% - 10min phone call
12:40 - 79% - 29min phone call
13:40 - 77% - 1 SMS send
14:40 - 74% - idle in standby
15:40 - 72% - idle in standby
16:40 - 69% - 5min MSN activity
17:40 - 62% - 3 phone calls with a duration of 7min avg.
21:30 - 54% - idle in standby
22:30 - 44% - 3 SMS send, 1 softreset just for the fun and some MSN activity
Then I went to bed and left the HD2 during the night in standby.. no 3G activity took place. Then this morning
10:27 - 26% - In bed and this morning I've browsed the internet through Opera and read some email. Also send 2 SMS messages
15:00 - 8% - Now I'm plugging my HD2 in the wall again.
The HD2 gave me 1,5 day. I think this is pretty exactable because of the heavy email polling with a 20 minute interval. Some average phone call activity. Just give it a try