The only differences I notice between Spiro's and Evah's are, Evah's only last about 18 months then their done. Spiro's depending on your taste can last many years. Evah's break in quickly, Spiro's take a while, and their a PITA during the process.
Arco with Spiro's will work in a Orchestra Bass Section, but soloing on them is a nightmare, at least for me. My take is the bigger the concert the more I rely on the FOH, and just use enough onstage for myself and the band to hear each other. I have
a Life Line but for straight ahead and contemporary jazz (whatever that means

) the Ehrlund EAP just sounds better, it is a piezo, but the tone is very different. My issue with a magnetic (at the time I was playing through a B/15 N(C)) is that
the timbre of the pickup through the amp is different than the sound of the bass in the room. For me, that's not acceptable regardless of the volume. I'm sure the Krivo sounds way better than the old Tonneinges 4 magnet I used to use. With my
5/8's Mirecourt (French) bass the magnetic I had actually sounded thinner than my Lakland's. So, I guess it greatly depends on your basses and what pickup and amp you are using. Just my take.