I'd give the Z3 Compact a miss
The Z3 Compact is basically the same as the Z1 Compact, which is going for £270 on Expansys.
The Z3 Compact is 4.6" rather than 4.3" (but still 720p) and is 300Mhz faster. The rest is the same.
The Z4 Compact is due out soon too, which ups it to a 4.7" 1080p and 64-bit Snapdragon 810.