Pix,
Just few things from my side:
Generally, for Nokia it is possible to use Common BCCH feature, which gives us opportunity to have only one cell with 2 bands. Usefull.
And I had official info from E/// and Nokia about SDCCH allocation for dual-band cells. It is possible to allocate SDCCH/8 at 1800 and 900 as well. So usage of SDCCH at inner cell also possible, if it required for some reasons(like traffic optimization for example).