Well, my friend and I used the same book, the German version of course. For I do not believe Griehl and Dressel produced books of different content in German and English language, I must do a meticulous comparison to show why we come to a very different assessment as you do. This may need to start a new topic about this.
I doubt sincerely that two translations of the same book can be so different that the narrative was completely different. I even quoted directly from the book. I suspect your friend is not reading the book through its entirety and is looking at the aircraft through rose tinted glasses.
If you and your friend refuse to accept the truth in English, how about in German. The following is from the German wikipedia page on the type, which is not as detailed as the English version. Yes, it is wikipedia, but it states pretty much what Griehl/Dressel states:
"Bei der Indienststellung der He 177 zeigten sich beträchtliche Unzulänglichkeiten. Als äußerst anfällige und von ihren Besatzungen nicht gern geflogene Maschine kam sie in den Truppeneinsatz, noch bevor gravierende Fehler behoben worden waren."
Das führte dazu, dass die überwiegende Anzahl der bis Juli 1943 gebauten Flugzeuge nicht frontklar war und aufwändig umgebaut wurde.
Google translate has this to say, for the non-German speakers...
The commissioning of the He 177 revealed considerable shortcomings. As an extremely vulnerable aircraft that its crews did not like to fly, it was deployed even before serious errors had been corrected.
As a result, the vast majority of aircraft built until July 1943 were not ready for the front and were extensively rebuilt.
From here:
Heinkel He 177 – Wikipedia
Here is the English version, a lot more detailed:
Part of the reason I have included these is because Wiki uses Griehl/Dressel's book as a reference.
...And if we are going to go on about this, this is what Hermann Goring had to say about the He 177 in March 1943. Written in English, but the German translation can be found easily.
"It is not only that the appearance of this aircraft is a year behind schedule, but that there is moreover no likelyhood of its becoming operational for the present , and that an aircraft which has been in development for years should suddenly present difficulties such as cannot be explained. I find this incomprehensible too."
Here's another source, Roderich Cesscotti, from an originally German written but translated into English text on the type:
Monthly output for both plants assembly line reached 12 aircraft by July 1943, and by the end of the year when this number had increaased to 42 permonth. Near the end of 1943, when 261 A-5s had already been built, an RLM order went into effect calling for the scrapping of all He 177s extant due to the high number of problems."
Finally, "By this time a total of 1,146 examples of this highly interesting aircraft had been built, despite never really having reached front-line maturity. The continuous technical problems which kept cropping up undoubtedly led to more losses than those caused by the enemy, and all hopes that this would be the bomber which could seriously compete on an even level with those of the Allies were brutally dashed."
"The He 177 began flying bombing operations starting in early 1943 in support of army operations... By this time there were 13 remaining aircraft, and despite their good showing with regard to defending themselves against enemy fighters, no less than seven further machines became total write-offs in spite of having notched up quite a successful service record. Most of these losses were attributable to engine fires, without any visible signs of damage due to enemy action."
Cesscotti goes on to describe the career of the type and by mid 1944 he states the following, "At this time operational readiness hovered around 35% on average."
"These notable examples illustrate just how much of a bitter disappointment the He 177's frontline career was to those who had placed high hopes on this weapons platform, which had such promising strategic potential."
need I say more. Your friend is clutching at straws if he pretends that the type's issues were not major and he is very much selectively reading from Griehl and Dressel to satisfy his own agenda and refusing to see what is blatantly obvious about the aircraft. It simply wasn't ready for continuous operational use in 1943.
An essay about what were the troubles of the He 177 and how to solve them, if the Germans had tried to systematically work on them.
How about your friend come on and do the opposite and prove just how the He 177 was ready for combat when it was not, with sources. Don't relay instructions from your friend, tell him to come here and do it himself.