i agree you don't want to replace the head unit. you want something other than LOC's to convert the signal. which processor to get depends on what you want to do. installing them and tuning them takes time and requires you re-configure the system.
The RF 3Sixty.2 is a capable processor. It's nice that it is compact, but you need to tune it via wireless devices - if you already one one capable of tuning, then great. if not, factor that into the price.
however, no amount of processing can fix a poor installation. drop-in's won't cut it. modifying the speaker mounting locations and turning them into rigid, dead speaker enclosures is key. tweeter aiming and placement is also key. make what you have sound as good as you can WITHOUT processing by physically improving their acoustical environment. after that, processing will be very useful and take your system to another level.
trying to add processing to a system with acoustical issues makes it sound weird.