Spot on Zen!

The only way to find out is to actually sit on them and ride...

I was lucky with the first seat we bought - I have the same seat now for both my bikes.

But if you bought one and it wasn't quite right after using it a few times, you should be able to sell in an online auction place like TradeMe or EBay... they seem to sell quickly and so you should be able to get some of your money back.