Hi Gem,
The orion and QHY5 requires a pc (laptop). Where as the synguider and nexguide are independent.
The question you really need to ask is; How easy is it for me to locate a guide star and focus?
There are plenty of reviews on all the systems you have mentioned, personally i prefer the orion autoguider ( i use one!) The reason being the screens on the synguiders are to small and obtaining focus and locating guide stars are difficult.
As Brendan said a 80mm refractor is a great scope to use, simply it makes it easier to find a guide star.
I expect to upgrade my dlsr to a ccd in the future, so using a laptop out in the field is inevitable, there are many other software resourses ie:
http://www.njnoordhoek.com/?p=325
Regards Paul.