It can be confusing so perhaps the best solution is see if you can get to a star party of some sort (a local meeting of an astronomy group). Then politely ask to try some of their stuff :-) If that doesn't work take a leap. Eyepieces are sold and traded here a lot so, given you know what's generally a good eyepiece (your research will give you that info I'm sure), go for it. My advice is don't necessarily try to fill gaps in the line up but upgrade the magnifications you like or use most. This depends on your interests: splitting doubles, planets/moon, DSO hunting, star fields. Look for exit pupils that match (around 1mm for planets, 2mm for high power DSO, and 3mm to 5mm for low power DSO say). In your scope something like a 4-5mm for higher powers, 10mm for higher power DSO and 18mm and up for lower powers. If your mount tracks you don't necessarily need a huge field of view, but lots of folks like the immersive quality of theses eyepieces (anything from 68° to 100°), and if your mount doesn't track the larger field of view can mean less nudging of the scope. A Zoom is great, but not necessarily everyone's cup of tea. Other factors include eye relief (particularly if you wear glasses while observing) and how well an eyepiece is corrected for abberations in the type and speed of scope you have. An f5 reflector will exaggerate some common flaws to a degree and the Televues, Pentax XWs, Vixen LVWs and the cheaper Explore Scientifics are built to minimize some of these effects (there are doubtless others too but these I have looked through). The Explore Scientifics were my first upgrade when dollar values were better and I was very happy with them. However if I had gone to a dark site more often I wouldn't have upgraded so quickly
A dark sky with a any reasonable eyepiece will show heaps more than a fantastic eyepiece in light pollution.