I haven used the HC7 but have the much older HC1 ( great build quality), and FX1 : in a different class.
I have also however used the HV20 ( and Still have the HG10)
I think that if the Low light performance of the HC1 is anything to go by, the HC7 is said to be better and I cannot imagine it will be bad at all
Th HV20 does have good low light performance ( and with it a little less AF hunting in low light C/W the HC1 ( not 7) , but I suspect the differences between it and the HC7 are down to personal preferences in "how it feels" and cost
They are far more similar than not and neither is in absolute terms "better"
As for 25P . I did not use it much on the HV 20 and don't on the HG10 to notice it makes a difference and it wouldn't be the deal breaker for me
Good luck