I updated a 252 and a 332 to 3.61 this morning.  I had no probems with either unit.  3.61 has some new option settings for RTK.  If you are seeing extended periods of RTK float mode, you change the default RTK config. from "USE ALL SAT" to "Use Highest Qual".  The following is from the release notes:

 RTK Mode selection
If you are experiencing extended periods of RTK float mode, first try the following
steps before using the RTK mode selection.
1. Move a few feet from your current position.
2. Ensure that you have a 100% CMR. If the CMR is any other value, this may be
caused by factors such as bad radio reception.
3. Drive away from a tree line or any source that may potentially cause multipath.
4. The RTK mode selection only helps when a user is in RTK float mode caused
due to GPS geometry and aggravated by terrain.

Selecting the RTK mode
1. Main menu:
2. Right arrow twice to go to the Configuration screen:
3. Down arrow once to go to the GPS Config screen:
4. Right arrow twice to go to the RTK Config screen:
5. Down arrow twice to go to Float SV Mode: Default: Use All Sats
6. Right arrow once to select/highlight and change the modes:
7. Down arrow four times and press Enter:  Use Highest Qual
Recommended if you are in RTK float for extended period of time