Most players, including me, think the Spider should be violently hit with a heavy shoe. There are also some who swear by it, instead of at it as was my case.
I use the L55 Rossa and get on great with it, it may not be the best one for you though, putters are a very personal choice.
The best way would be to rent them both for a few days, you need to play quite a lot of rounds to discover whether you like a putter or not. It may be cheaper to just buy them both, play each for a week and then sell one.