Works as a house rule, for sure. Might want to make it Rating * 3, as under the Core book rules a Rating 6 drone could run 3 x Rating 6 programs and under the Rigger 5 rules the same drone could run 6 x Rating 6 programs, whereas under your house rule you could only run 2x Rating 6... never mind, you squared Pilot, didn't you.
So a Rating 1 device could only ever run a single Rating 1 program, and a Rating 6 device could run 6x Rating 6 programs. A rating 2 device could run 1 rating 4 program or 4 rating 1s, and so on.
I like the versatility, but I've always disliked more math, so I'd just stick to the Rigger 5 rules especially since a drone slaved to an RCC can use the higher device rating of the RCC for purposes of max rating.