not really. The current pricing $/watt makes a lot of sense. You just have to remember that whatever module you buy, it will be a rare occurance to see the nameplate rating from it (you usually will see 75% of it if you are roof mounted, and more if you are pole or tilt array ground mount). It is possible, but rarely happens. Testing is standard nowadays at 1000w/m^2 so the performance of most modules on the market will be the same. Amorphous is a little different animal as you have found out. Although all modules are rated very similarly, amorphous has slightly different temperature coefficients than other types of modules, and there fore a little different power curve across similar ambient temps. Low light performance is usually better with amorphous modules.
-----"A 100W, 16V panel typically puts out more current than a 100W, 25V panel, for example."
This is not true. We should be talking about watts here. not current. The voltage and current will be inversely proportional so if the wattage stays the same (cant remember the last time my 100 watt module became a 150 watt), the voltage and current can fluctuate, but will always add up to equal the wattage. Basic Ohms Law stuff.
say we have a 100w module. It can only do 100w @1000 w/m^2.
Now say, the solar insolation is only measured at 800 w/m^2 This means we can only generate 80w with our module.
If I used that module on a 12v battery, I would see 6.66A of current. If I used the same module on a 18v battery (not very common) then the current would be 4.44A. Either way, its the same wattage with the same module, with the same sunlight intensity.
Hope I didnt confuse you.