Do you have some links for this Whittle bypass? And it is engineers in the aforementioned publication I cited who refer to the Jumo as having "at least 7% bypass" and they remark about its uniqueness (again as mentioned bled from the area of the 4th compressor stage, this is an important distinction), and the variable geometry exhaust cone, my commments simply reiterate what they wrote about it. Perhaps you should be arguing your point of view with them?
Genesis of the Jet by Golley is a reasonable telling of Whittle's story. Its got quite a few pictures of various engines with fans and reheat. One of them is patent GB471368, which has a fairly bizarre fan arrangement. A much more rational design was the LR.1, which was the second high bypass turbofan to be designed that I'm aware of. Power Jets were almost finished building the prototype when they were nationalised and work halted. It was a two spool design with a bypass ratio of 2.5.
The Development of Jet and Turbine Aero Engines by Gunston has the same drawings and a few others.
The claim of 7% air bleed for cooling is repeated in quite a few publications with exactly the same sentence used. I've no problem with that, but air bleed doesn't make the 004 a turbofan. There is a similar air bleed for Whittle's designs, but this just isn't mentioned. I had to a have a good dig for a picture in the right orientation to show the cooling fan but eventually found a cutaway of the Nene. The cooling fan is mounted on the main shaft between compressor and turbine. The air was used primarily for turbine disk and bearing cooling.
http://www.flightglobal.com/airspac...ls-royce-nene-engine-installation-cutaway.jpg
Here's a really obvious cross section of the Metrovick F2 showing the path of the cooling air thats bled off the end of the compressor.
http://i25.photobucket.com/albums/c84/AviationImages/MetropolitanVickersF2.jpg
The variable geometry exhaust (not a new invention) was looked at for the UK engines (and variable geometry inlets) but simplicity was preferred given the small difference in thrust available (From an article in the RAE journal a few years ago). Its only when you have much higher temperatures that the pressure thrust becomes more important than that from the mass flow.
I'm not so sure about the Russian's being so enamoured with the 004 and 003. What I've read on the subject (which isn't a great deal given the limited information not in Russian) seems to state the opposite. Yefim Gordon in Soviet Secret Projects: Fighters gives a summary of jet development indicating that the Russians weren't very happy with them. They did manufacture some improved versions with reheat which powered quite a few of the early postwar prototypes.
It is perfectly clear to me, and clearly outlined in authorative, detailed publication the Jumo was far from inferior and was an excellent design with a poor reputation wholly achieved by a lack of strategic materials and the circumstance of late war German industry.
The best source I've found on the 004 is "The Development of the Junkers Jumo 004B—The World's First Production Turbojet" by CB Meher-Homji in ASME journal. Its quite clear in there that most of the problems were due to design (compressor vibration, turbine vibration). Better materials would only improve life of the hot section by less creep, they wouldn't solve the other problems. Build quality isn't that great either on the example I've looked over and that probably adds a bit.
Compared to the Metrovick F2, which was a contemporary allied axial design (not the later F2/4)
Thrust: 1980lb for the 004B (though later uprated a bit to 2200lb, and 2640lb in the reheated 004E). 2150lb for the F2 (later increased to 2600lb, then 3850lb with the F2/4 with an additional compressor stage)
Weight: 1650lb for the 004B (some sources give 1585lb which seems to be without cowlings) 1500lb for the F2
sfc: 1.4lb/hp-hr for the 004B (which would be higher for the higher thrust, higher temperature 004E) 1.07lb/hp-hr for the F2
Compressor: 8 stage axial for the 004, 9 stage axial for the F2
Pressure Ratio: 3.14 for the 004B, 3.5 for the F2 (indicating the F2 should have lower fuel consumption but lower thrust)
Mass Flow: 46.6lb/s for the 004B, 45lb/s for the F2
Compressor efficiency: 75-78% for the 004 (actually lower than Whittle's centrifugal types, just), 84% for the F2
Combustion Temperature: 775°C for the 004, ~750°C for the F2 (indicating the 004 should have greater thrust but higher fuel consumption)
Turbine: single stage for both (no fir tree roots on the 004 though)
Turbine efficiency: 79.5% for the 004, 90% for the F2 (mostly because the F2 had free vortex blading)
I think that's a pretty comprehensive comparison; the 004 doesn't look that great alongside the F2.
Source for most of the F2 stuff is The Early History of the Aircraft Gas Turbine in Britain by Sir William Hawthorne.
The 004 had some nice features, the integrated starter motor with pull cord is great, and the Germans made big contributions in some areas like air cooling for turbine blades (alongside AA Griffith), but you can't get too carried away with what was actually produced. The 004 was a fairly simple design, able to be produced in large numbers, which is what was needed. It's actual performance wasn't that great compared to it's contemporaries - but it was enough.