All OGC interface standards (WMS/WFS/WCS/WPS/SOS/WMTS) operations are stateless and cacheable irrespective of their encoding
. So there is no gain or comparison to be made here.
It is moot whether the so called WMTS RESTful
encoding is indeed RESTful
, as a client seems to require out of band information, i.e. information other than that provided in the hypermedia, which is an anti-REST pattern. So really your choice of encoding is purely personal choice.