I feel that taking MRT CCL/EWL from Serangoon to Changi Airport is
still the best way. Taking 103/103M to Jalan Kayu and transfer to
858 does't really make much difference compare to taking service 53
direct.
Being a resident in Serangoon Nth area, SV 103/103M plays a major
part for ppl to transfer directly @ Jln Kayu to go either East
or North.
From my experience, SV 53 to SRG & SV 858> SV 103 to SRG
are same. But SV 858 will chiong on expway, which is the best
part.
SV 103 route serves as a good linkage to jln kayu for direct
xfer to SV 168 to go straight w'land & other services to go
Yishun, Sembawang, Chongpang and so on.
Just 2 cent worth of thought, no matter wad the rationalisation
of services will be done asap by first quarter of next year. So all
we can do is wait & see the service changes.
Hopefully new services is introduced to involve linkage, but
imo, the new interchange is really damn small!