I had used a fish8840 version that worked well until I ran over it with a chair. I have read some negative things about them, but it seemed to work ok for me. (I was able to update the firmware w/o issue)
My current one is a "gm328a" version from ezm electronics studio... All surface mount. it, too, worked well for me, until...
I don't know if it was due to upgrading the firmware to current version, or the hardware, but I tested a diode that looked similar to one that was broken on a pcb (hoping to gleam some info to buy a similar diode) - however, I was able to test it once and got a reading; but after that, the diode failed all tests, using a dmm it registered as about a 1 ohm resistor in both directions...
(Trashing a diode is another reason I'm looking for a new version...)
Both the versions I had, had the mpu soldered on, but had provisions for an ISP header (but no header) -- as I recall, both headers ended up being on the bottom, so it's not something you want to leave on the tester. From what I can tell; you want a socketed chip so you can replace it if they locked the firmware... but I am a novice there...