RB-700 Counterweight: Stock, Express, F2, Michell?

Trying to decide on which counterweight to replace the stock weight on my RB-700 tonearm.

Expessimo Heavyweight
Kerry Audio F2
Michell Tecnoweight

Leaning towards the F2 - the Michell makes me quite nervous about hurting the bearings on the tonearm when removing the stock stub.

Any help would be greatly appreciated - too many decisions!
If you are concerned about the bearings with the Michell have an expert do the installation. It is quite simple; did it to my Audio Note ARM2 (rewired rb300) with no problems. The arm sounds a bit better; bass is more solid.
The Kerry Audio F-2 Titanium Heavyweight Counterweight definitely astounded those who heard my lesser model RB-300, before and after. Self install in minutes, and you'll be pleased. You can check past Audiogon discussions where there are a lot of rave reviews, including my own.
Thanks for the input! I found a great deal on the F2 today - I'll report back once I've got it installed.