OK, so I was looking to buy a pair of studio monitors primarily for mixing/tracking/production of my own music and secondarily for a neutral medium with which I could fine tune my modeler's presets and maybe enjoy music through them.
I get anything from zero to some hiss but that depends on the room I use them and the outlet configuration so I know it's not the speakers that may or will cause any hiss (always TRS connection and volume set on max). So, that's that.
I use them in untreated 12-20 square meter rooms, volume wise there is no way you will ever need more volume than they can provide even if you want to throw a small party in the house (50 square meters).
Now, the most important part, the frequencies themselves. There are dozens if not hundreads of monitor speakers out there that are supposed to be flat but they are all different. The trick here is to pick the ones that fits your work in terms of sound fidelity, if you can, and if you own more than one set of monitors so you can cross-reference (different brands/models) that's great too. I find the E5's very balanced, not mid heavy than some of the star monitors out there, not high heavy and not bass heavy either (always by my standards, again, ymmv).
OK, now for the the bass freqs comment since most people out there may think that 5" monitors can't cope with those. Let me put it this way, If you love super accentuated bass freqs, and I am talking about freqs that don't even exist on an original recording (no matter if it's your creation or someone else's) then for your own good just forget all about studio/reference monitors and just buy big HiFi speakers, you will be more happy with that choice. If you are instrested in listening excactly or close enough of what has been recorded and your room is not humongous and you are after a nearfield pair of monitors, then the 5" ones will do just fine and in some cases way better than most of the bigger ones. And if your music consists of sub-bass freqs just look for something else (studio moniors + subwoofer, bigger studio monitors etc.).
The music I record comes from electric guitars and all of them are tuned in standard D, electric bass with 55-110 strings tuned in standard D etc. I can hear everything on the E5's and pretty much as they were recorded. In fact as I am writting this review, I am listening to some Miles Davis mid fifties music and I can hear the uptight bass loud and clear (and that's with -2db on the bass freqs due to speaker placement).
All in all, sorry but no, the E5's are not the "bestest" of all, there is no such thing. They are VERY balanced and sure a pair of HS5's (more mid and high heavy in my opinion) or 305's (somewhere between the E5's and HS5's in my opinion) may suit you more but those have the best balance for what I do.
In conclusion, If you'll be working in relatively small rooms, you don't want to break the bank and your main focus is on mixing/tracking/production (as long as you don't care about sub-bass frequencies) then those should be one of the first candindates.
EDIT 2022: after just two years of moderate use (apartment, low to moderate volumes) they crapped out. One of them lost a lot of volume comparing to the other (about 25%) while the other became scratchy at certain frequencies (clean electric guitar). I RMAed them and sent then back to Thomman which in their opinion they were fine and couldn't find any faults. When they sent them back to me, one was totally inoperable as it was like only the tweeter was reproducing any sound and that at no more than 5-10% of the nominal volume (so almost quiet) while the other had the initial freq issues. I have taken them to a local tech just in case they could be repaired and I just bought a pair of Kali Audio LP6 v2 instead to do get the job done. All in all, NOT happy with the Thomann service this time around and surely NOT happy with the Presonus reliability. Heck, I had a pair of 5" Tascam monitors for more than a decade with the same use and they were just fine after all these years.