vaping is extremely subjective... Whilst there are major differences between devices, a certain amount of mis-information abounds on ECF. The latter is propagated by neophytes watching too much TV IMHO. Although things are called eGos, they do not all perform the same, as well as the quality of said products.
When the eGo hit the streets in the spring of 2010, there were only 2 models. The eGo and the Tornado and all was relatively simple. Of course here in Canada we had the Happy eGo (sold by Happy Jack) JoyE allowed distributors to name the eGo as they wished. In the beginning that was not a problem as stated, there was the eGo (Janty) and Tornado.
The first knock of was the Riva (although it did not carry the eGo name) It employed a 750mAh battery, one that was rejected by JoyE as not meeting specifications and had proven faults and some safety concerns. JoyE does not make batteries. The Riva employed PWM although folks toted it as a 3.7V batt, nope. Until recently (probably ran out of the rejected batteries) and starting with the Riva SE, Riva's are no longer PWM. ETA: Riva batteries had a fairly high failure rate compared to JoyE products.
One of the nice things about PWMs is, longer atty life

The pulse modulation and width is so rapid that it is insignificant to the vaper and the 3.7V subjective. I have regular eGos, an 18650 eGo and a VV PWM eGo. Although the 18650 eGo will outshine the normal eGo, it is short lived and the current supplied wanes over the battery charge, whereas the eGo delivers the same voltage of 3.0 and 3.7 over the battery charge. OTOH my VV eGo delivering 3.7V regulated and modulated is miles ahead of both the eGo and 18650 eGo. Why? Because to produce 3.7V it is probably pumping at 3.5-4.2V, dunno. I don't have an oscilloscope and the data is insignificant to me.
My original set of batteries on my eGos lasted me 14 months, pretty darn good. OTOH I never vaped anything but STD attys on them. LRs well that's a different story. Folks are and can, but the battery cannot withstand the current draw and longevity is reduced.
What we haven't seen since the fall of 2010 is vendors selling and claiming genuine JoyE products on items that were not JoyE. BTW JoyE is cleaning up the streets. Does this mean that other branded eGo products are garbage? No. It just means that you get what you pay for. $3 dollar atties from Eastmall perform like $3 atties and last $3 dollars worth
One example the Elipse sells for $109 (JoyE) and the competition sells for far less. Does this mean that the Ovale product carries an 580% mark up, or that the knock offs are exactly what they are, a cheaper substitute in design and performance.