As far as I know, the only other differences between the early (440C) Grips, and the later versions is, the early knives that were colored were painted. The later versions have the color molded into the scales... The pocket clip logo is also different. The early clips are marked Benchmade USA. and the later versions dropped the USA and just say Benchmade.
I bought a Mini Grip in 440C right after they came out. I carried it every day and used it hard for a few years. It held up very well. It would take a very good edge, and keep it for a decent amount of time.
I picked up a couple more, and have been carrying one of them for probably six months now.
Personally I haven't noticed any real difference between the 440C, and the 154. But in all fairness, I've used 440C more than their 154