OK, I'll start off by saying I love the PC-11, its a true component boombox, that separates and is very well built, similar to PC-3, 5, 6, 55, 550. The only drawback of the PC-11 is its 5" full range driver. I'm willing to wager that the PC-W300 with the 2 way speaker system has a better frequency range thus having a better sound.
The PC-11 frequency range is 75-17,000Hz according to the spec book and the speakers are rated at 15w RMS @ 6 ohms. So that means its not gonna shake the walls, but the mids and highs are good.
I'm not sure of the W300 performance, but I'm sure someone who has one can chime in.
Some other things I noticed are the following;
PC-11 has a 5 band SEA Equalizer, the 300 has separate bass and treble.
PC-11 has a single tape deck with no auto reverse. the 300 has dual deck with auto reverse
Both have Dolby B, Super ANRS, and are Metal tape compatible.
Hope it helps.