I'll still take the "Kaplan" non whistling E and the "FM" E.

And the band played on.

Ken.

Indeed I'v heard of many people that are avid fans of the Kaplan E.

However, keep in mind that an E string may change your whole perception of your instrument's sound. Many powerful but not tinny E strings, especially the high tension or heavy gauge ones (stark/heavy/forte or something like the Evah Pirazzi mittel silvery steel E) could make the rest of your strings sound fuller and deeper.

It's been a really long time since I last used Helicores, but in synthetics here is what some strings do:

Pirastro Gold Label Wondertone (Medium): Silky feeling, almost never squeaking, pliable feel relatively to other contestants, brilliant and projecting sound

Pirastro Eudoxa plain steel (medium): More powerful and direct than the previous. could be "bright or dark" depending on the instrument but not "brilliant or mellow". Somehow it feels colder and more straight forward

Pirastro Evah Pirazzi silvery steel (medium): The screamer. If your instrument can match this, and not sound overly bright, it's a decent choose. Supposed to be high tension, but it feels somewhere between the above two. To me at least. Really powerful, really projecting. Every time I used it, the ADG seemed considerably more mellower, even the "bright" sets like visions.

Pirastro Obligato gold steel (medium): The most mellow and softest, but expensive. Something about 10 USD I guess. A fancy gold string, could open up the ADG but it's prone to whistling when not careful.

Pirastro Eudoxa aluminium wound (medium): Could be a good match if you want a feeling like "do you mind If I play? " . Just joking. Quiet and mellow, but mostly a match for low tension synthetics or gut.

Pirastro Eudoxa aluminium wound (stark): Big. Bold. Tense to me. It's mostly me, but it felt like "thick". But some may want this. Never ever squeaked though.

Pirastro Evah Pirazzi Gold : Big, Brilliant, Powerfull. It's higher tension than the other medium gauge Es, imagine something like the Pirastro Gold label E pimped up.

Thomastik -Infeld Vision Titanium Orchestra: One of the best I've ever used. It was bright but not tinny, and the softest ever. Reaching the highest position was always a joy, even on poorly shaped fingerboards. But...you know. a little expensive.

Thomastik - Infeld Dominant (medium): Most people describe it as a scary E. Truth is it could sound weird when pushed a little harder, but it could be a match for really bright strings. 

D'addario Pro Arte (medium): While the rest of the set felt tense and quiet the E worked really well with other sets, being reliable, and brilliant, not empty or tinny.

Hint. You have to buy a few, to check what you like under your fingers of course. And what works for your instrument. Fortunately the are cheaper than whole sets.

Fiddlerman said

I have the opportunity to try these E strings on hundreds of violins a week.

I don't know how it feels like when you have to do it every day, after some time. But it sounds like heaven to me. 

Shouldn't there be a "string tester" profession? like those folks that test wines, cheese etc. I would apply for it asap. 

Fiddlerman said
We would love to have you.

That would be my honour

Regarding the first post in this topic, I have noticed sometimes that the way the e string contacts the bridge can make a difference, on some violins, (or on some ears), besides the choice of brand of course.

This plastic little tube that prevents the string from cutting through the maple (when your bridge doesn't have a parchment or another material in the E slot), slips back and forth during the tuning, and sometimes collides with the string when it vibrates, and it may sound a little strange. 

well, with all this talk about Westminster's, I went down this morning and picked one up and switched it out with my Prelude E on my China violin. and yes, I did turn things a bit darker/warmer and took a bit of ringy ness out of it, which is ok with me, I had forgotten that the Westminster's have a bit of a silvery sheen on them, as opposed to the Prelude which is clear. Some E's have that 'sheen'. Kinda nice for a change. I like characteristics of both of them, but a change is nice once in a while.

My old German has Parchment, but the China does not. I use the larger diameter tubes from Dominant E's. Partly because The bridge notch is a bit worn down & a bit wide, But I'd use the Dominant sleeves anyway. I like the E string to sit up a bit, even if it is within the correct parameters for height. As long as it's not putting the intonation out (which it isn't) I'm ok.

I'm not about to put a parchment on the China (if it ain't broke, don't fix it) and I don't want to risk ANY changes, as it seems that if things are working good as is, any change of any kind, usually works out for the worse. At least that's been my experience more often than not.