Based on a SBST BC, the Mark IVs are used only for one reason,
that is because Singapore buses going into Malaysia cannot be too
fanciful or else Malaysia is going to be jealous as they only have
Non-WAB buses.
I think is more of worrying that the bus might be stolen instead...

I have to diasgree with you. I strongly believe the Mark IV
DM3500 & Striders are use as a stop-gap measure. Meaning to say
that it's a temporary measure until a full fledge of 80-90(50 For
170, 30 For 160, 10 Spare in BBDEP) new & suitable bus model
can be found for the 160/170. I'm hoping that the Citaro will do
cross border in the future because it's really a good steady bus,
vs KUB, somehow i feel the KUB bodywork is very light as compared
to EVObus/mercedes Benz bodywork.
For me I'm looking forward to seeing them go cross-border and
hope there will be enough DM3500/Striders for both routes esp 170.
The desto plate(old plate on MK 3 or the common font plates found
on 74, 157, etc) and the new side rectangular plate will be
something i would want to see as it comes on svc. Wonder how the
Blue Side rectangle plate(For kranji mrt to Kota Raya) will look
like ?
No, Citaros for Singapore use only.