To me, the debate between Gilchrist and Dhoni doesn't come down to batting or wicketkeeping - it's about bowling.
Let's assume we've got an XI that looks somewhat like this:
1. Tendulkar
2. -
3. Ponting
4. Viv
5. Miandad
6. Bevan
7. -
8. Wasim
9. Garner
10. Bond
11. Murali
(These are primarily placeholders; no debate required about the particular batsmen).
With a line-up like this, you need another frontline bowling option, and you need a wicketkeeper. Your options are Dhoni at 7 and one of Watson & Jayasuriya opening, or Gilchrist opening and one of Klusener, Symonds, Flintoff, Cairns, Imran, Kapil, or even Shakib.
To me, in this situation you go with Gilchrist opening and keeping, because while him and Dhoni are pretty much locked on par as ODI wicketkeeper-batsmen, it lets you select a stronger fifth bowling option (because I don't want to rely on Bevan/Viv/Sachin for 10 cheap overs against the Martian XI).
If you drop Miandad or Ponting from that XI, you can play Dhoni at 5, Bevan at 6 and open with Amla or Turner and not worry about a lack of bowling.
To me, that ATG ODI XI looks better with Gilchrist opening and Kapil at 7 then with Watson opening and Dhoni at 7.
Let's assume we've got an XI that looks somewhat like this:
1. Tendulkar
2. -
3. Ponting
4. Viv
5. Miandad
6. Bevan
7. -
8. Wasim
9. Garner
10. Bond
11. Murali
(These are primarily placeholders; no debate required about the particular batsmen).
With a line-up like this, you need another frontline bowling option, and you need a wicketkeeper. Your options are Dhoni at 7 and one of Watson & Jayasuriya opening, or Gilchrist opening and one of Klusener, Symonds, Flintoff, Cairns, Imran, Kapil, or even Shakib.
To me, in this situation you go with Gilchrist opening and keeping, because while him and Dhoni are pretty much locked on par as ODI wicketkeeper-batsmen, it lets you select a stronger fifth bowling option (because I don't want to rely on Bevan/Viv/Sachin for 10 cheap overs against the Martian XI).
If you drop Miandad or Ponting from that XI, you can play Dhoni at 5, Bevan at 6 and open with Amla or Turner and not worry about a lack of bowling.
To me, that ATG ODI XI looks better with Gilchrist opening and Kapil at 7 then with Watson opening and Dhoni at 7.