Not really. 
I get that the 4 mains and the 2 lines leading to the Y come out at the same level in the photo (Jan 2011 issue of MR). However, they are "rising" up in the direction of the arrows you added because they need to allow clearance for the tracks you outlined in blue coming from the turntable to crossover. From what I can see, there is a wall of some sort to the right of the turntable along the 4 mains and they don't reach full height until they get past the end of the wall. At that point, they and the other visible tracks are on the same level. The 4 mains go beneath the layout to form the 2nd level. The 2 lines from the Y and the storage tracks attached to them go further beneath the layout to form level 3. This is shown in the inset where the 4 mains are obviously on top of the 2 lines from the Y.
I picked a 7" separation between levels to allow access to rolling stock, etc., in case of a derailment or other problems. That might be more than you feel you need, but I had to use something. In any case, the 4 mains have to drop at least 5" BEFORE the crossover, depending on what you plan for sub-roadbed and roadbed. Either way, the descent HAS to begin somewhere in the loop at the bottom of the layout and where the descent begins in O scale may be far different from where it began in HO scale.
While the 4 mains and the 2 lines to the Y appear to be at the same level coming up in the drawing, doing so places several turnouts on the grade. That is usually frowned on, but in this case you wouldn't be uncoupling cars on those tracks, so it probably wouldn't matter. However, the 2 lines to the Y still have to drop twice as far as the 4 mains and they have to do so BEFORE level 3 crosses under level 2 coming out of the curves at the top of the inset. Level 2 drops at least 5" and level 3 drops at least 10". I simply don't think there's enough length for the 10" drop. Call me crazy, but dropping 10" in the same distance as dropping 5" should result in a grade that is twice as steep, and too steep to boot.
Oh, and I forgot to mention I substituted the turntable in my version because for some reason I couldn't connect any tracks to the one you used.
Since I don't like RRT's 3D display, I might put this in SCARM to see if it's 3D display will better illustrate what I'm trying to say.
