Hi guys,
khashyatc, I'm with Scooby, you can/should use one of the procedures in case you have radar coverage (PSR and/or SSR).
Regarding the other question about giving radar service and procedural service in one same sector, is all about the coverage. In the Canary Is. we use to have a sector with 1/3 radar coverage (hence giving radar service), and the rest without it, providing separation and spacing between aircrafts with different FL's or time estimates (mach num. technique). Now we have a full procedural sector by itself after changing the configuration of the FIR/UIR sectors.
Hope it helps!