You said that 60-70% is good enough but personally I think it does border on line of having problems with low quality.
The only way you would know for sure if it's just solo2 is more sensitive about low signal quality is can you check with a neighbour next door or someone else in street and see what their signal quality is like. For sake of easy reference always compare same channel as some channels may be higher/lower than some others depending on satellite/transponder they are on.
If neighbours is a lot stronger then you know that yours is bordering on the low.
For reference what percentage is your strongest signal (that you have noticed) and what is your weakest?
UPDATE:
I will say though when I moved into our house, the old satellite was providing about 80-90% on BBC1 (I generally always use a FTA channel like that for comparison). I got an offer of free sky tv for 1 year if I moved over to them and bring my line and broadband over as well (from o2) so I took it. However, as I was getting free sky for a year, I removed the satellite dish/LNB but kept cables (couldn't be bothered removing them all and instead covered the cable ends to prevent water ingress).
Now with a new satellite and LNB (I believe the satellite dish is around the same size as old one but the LNB was newer), I now get 99-100%.
This may have been down to combination of new dish/LNB and/or simple fact is that Sky aligned the dish. I will never know for sure.
