Hi Barrick,
Based on your description, I think instead of slowing the simulator down with the Sim Rate Multiplier, you'll have a better simulator experience by slowing the cyclic response of the heli. Here's how to do this:

Begin by selecting the vigor transmitter and click "edit" FSOne will tell you it cannot edit the original and you'll need to make a copy. Name it whatever you want to.
After the transmitter is saved the edit transmitter window will open. In the upper right portion of the screen you will find a button named "mixing". Click on this. (by the way, these settings are specific to this transmitter only, so you're not making global changes that would affect the entire sim... just this transmitter). Now click on the mixing for the CCPM120 and click the "edit" button. Now change the rates for the Collective Chan Gain to -.35 and the Roll Chan Gain to .45 and the Pitch Chan Gain to .45 (The closer you get to 0 with these values the slower the heli will respond - I did not try these values, so I'm just guessing, your mileage will vary). You'll notice that you'll have to click in the cell and backspace and retype the values, that's normal for FSOne. Make sure the Collective Chan Gain is a negative number or the mixing will be all messed up.
Okay, Click ok in that window
And, Click ok in the next window
And, finally click Ok in the upper right hand corner of the Edit Transmitter window.

This will take you out to the Transmitter selection window and click ok, Click ok through the rest of the windows and try flying to see what your changes were like.
Let me know if you don't mind what settings you like the best.
Happy Simming.
Scott