Actually for 860, if SMRT can manage to run it with a full A22
fleet at such high frequency without DDs, I think the route might
not be DD-friendly?
After all, 860 is BSEP so LTA
would have defintely done something to deploy DDs on the service if
it could , given that 983 has DDs (comparing case to case, given
some circumstances). Even if AMDEP was not DD-friendly before, LTA
would have made SMRT deploy from WLDEP for 860 if it could IMO.
Definetly its gonna cost SMRT and LTA more to run so many A22s on
that service as opposed to a mix of SDs/DDs right. Only advantage I
can think of for maintaining full A22 fleet is the service
efficiency, but I dont think LTA has cared too much about
that.
When LTA starts to take those BSEP buses away from SMRT to
handover to TT and SMRT has to deploy its own fleet, maybe SMRT
will consider bendys for this service, be it O405Gs or A24s.
How is the route not DD friendly when 850E runs DDs along Ring
road stretch towards Khatib?? 
How many services would LTA/SMRT transfer to WPDEP bcoz AMDEP
cant take in DDs? In meantime, didn't have choice but to go on
adding A22s. 
Even after transfer to TT, doubtful 860 will get many bendies...
A24s order is so little that it is out of question... and 860 is
WAB so all the non-WAB bendies are useless... at max 2-3 can get
deployed... So sooner or later 860 needs to get DDs.
Also we have to note 860 loading is crazy even though the flats
from st 41 to ave 4 on both side of ring road are still under
construction. Once they are ready in 2016/2017... 860 will be more
like 291 fleet with maximum DDs.