I am speaking from my own personal experience. I had a A95 5MP then while on a wk end trip it quit just like that, so I was forced to go a local store and bought A570 and really enjoyed, but since I am going to Guatemala I wanted more Zoom power and I didn't want to take my Dig SLR, too risky for that area.
So I bought the SX100 and granted its only 1/2 MP over the A570 but the 10x optical is phenomenal. As far as the viewfinder, I guess ever since I got the A95 I used the LCD and is not a big deal to me.
I shot 20 frames on the SX and let me tell you the zoom has a great reach, and kept it at Auto ISO. I bought the black SX100 and somehow it looks more like a mini SLR if you ask me. The only thing I wish is that it could shoot RAW but then again it would be overpriced in the after market like the G7, and also I wish it had a rotating LCD