The operating policy in my company (BA), is to 'give consideration' to selecting flap 2 when atc request a speed between S speed and Vls on the approach.
I personally prefer this approach, ie to leave it to the pilot 'on the day'.
I think it depends on the prevailing conditions and flight profile.
Personal reasons for taking flap 2:
- above the glideslope (goes down better with F2)
- in icing (incr thrust with TAI on)
- in turbulence (better margins)
- if more than about 15kts below S-Speed
Personal reasons for sticking at flap 1:
- smooth air conditions
- more than 8nm to touchdown and below glideslope.
Just my thoughts....