I play 85% arco. I play in Orchestra London Canada, the Stratford Civic Orchestra and the Light of East Ensemble (Middle and Near East music most of which I bow).
I use a KSB Tecchler German bow with black hair and Kolstien soft and/or Oak soft rosin. Presently I'm using a Peter Chandler bass - Tarr model, a 7/8 bass with a short 39.5" string length. It came with D'Addario Helicores on it. They were really dull and unresponsive, very quiet and the pizz was half the volume of the arco.
I did some research and chose Piastro Obligatos next. Wow, what a difference! Pizz like a canon, easy to push down with the fingers, stayed in tune, sounded great, bright sounding so it was easier to hear the pitch. On the negative side, because my short string length, they were a bit flappy. The roll on the A and E strings sometimes made 1/16 note passages unarticulate. Other than that, I was very pleased with them.
Looking for a stiffer string, I did a bit more research and picked Thomastick Dominants next. I found they were stiffer so I could lower my string hieght a bit and were not flappy. However, at first they had an abrasive, nasal metalic zing when bowed so I had to be really careful when playing arco. I took about 2 months of playing till they mellowed out. I liked them a lot after this. Again, they are quite bright so you can hear the pitch well. They have lots of volume and the tone is quite nice, although a bit plasticky. And they stay in tune forever; I almost never had to tune!
When these started wearing out, they great Evah Parazzi and Belcanto megathreads started. I thought I'd try one of these. I flipped a coin and it came up EP.
I've only had them on a week and have done only a "New Years in Vienna" Pops gig so my full review will have to wait a while. So far though, I quite like them. My stand partner noticed my bass sounded better. Our principal bassist tried my bass and the 1/16 notes really popped out.
I looked at the ball end of the strings when I was changing them. Compared to the Dominants, the perlon filiments seem finer and the inner copper wrapping is flat rather than round wire. The guage is a little larger as well. I had to take a round file to open the groove on the bridge for the A string a little so the string would settle right to the bottom. I haven't put on the E string yet as I'm going to have some extension work done but I imagine I'll have to trim the bridge for that as well.
So far, they seem to have the best of the Obligatos and Dominants without the negatives. I'll write a full review after I've ripped the snot out of them with Beethoven's 5th and Brahms 2nd. I'm giving a big solo concert next week so I'll see what the audience thinks as well.