As a personal practice I use crimp type devices over wire nuts, split bolts or terminal lugs. Connection blocks need a large amout of space in my opinion to make room for servicing the connection in the future. If there is an isue of multiple splices I would the use a termination box. Last, an approved splice replaces the insulation charactoristics of the cable. Not only voltage, but temperature and environmental protection. A double layer of half lap rubber followed by a double layer of half lap 33 covers a large percentage of insulation types.