Well David, of course it is just conjecture, still to be proven, at this point. But here is my reasoning.
First, the bearings. The bearings are said to be better than the Silver, but since the Silver already has bearings as good as most very high-dollar arms anyway, I really doubt that is going to have an effect. Both arms have their bearings located in the saddle, at wide spacing, similarly. So, I estimate the bearings to be a tie, in real-world effect. I could be wrong, and there might be a slight edge to the Encounter here, but only as much as you could hear the difference between ABEC 4 and ABEC 5 bearings. Not much.
Next, the arm tube. The Encounter has a different tapered tube which may actually be better than the Silver's tube, as far as resonance control. I don't think the stiffness differences of the tapered tube will be a factor. So, the Encounter may have a slight edge in arm tube resonance, but we'll have to see if that is the case or if it makes an audible difference. Possible edge for the Encounter here.
The end-stubs are the same on both arms.
The major factor that I see in the improved design of the Encounter is the massive bearing housing. While this looks like it will provide a "very strong" support for the arm bearings, in fact that area doesn't really need to be all that strong. It is plenty strong enough in the Silver to withstand any possible deformation of the bearing saddles, at the forces that are present there. But, it does provide a certain amount of added lateral mass, which provides an increase in performance that is aimed at doing the same thing as my HiFi mod. Here, the question arises, does it do the lateral mass thing as well as the HiFi mod? This is what I want to see. Frankly, I don't think it will do as well, because the mass increase on the Encounter is located almost entirely within or around the perimeter of the bearing saddles. It does not extend outward beyond the bearings to any extent at all. I'm not sure of the material they used yet, but it is likely to be aluminum from the looks of it. So the Encounter's lateral mass increase is a lighter material and not placed as wide as the HiFi mod. There may be some more material there, but it would have to be alot to overcome the difference between lead and aluminum. Also the positioning is very important, because the force is increased by "mass times distance squared" calculation. So the higher mass, and the distance from the center pivot, are key factors. My mass increase is much wider and therefore exerting much higher static moment in the lateral plane, than the Encounter is. The result of this, is that my modded arm has the ability to stabilize a higher force of stylus excursion, before being moved laterally in an unwanted fashion. Since I already have tested and used my mod, I am certain that this level of static moment in the lateral plane is not causing any problems to the normal movement of the arm. So as long as the mod doesn't impede anything, it is not too much force. Also, since my weights are attached to the actual ends of the bearing axle, they provide mass and damping to the axle itself, and make it nearly impossible for tha bearing axle to be excited by any arm vibration, which could cause bearing chatter. Chatter is virtually eliminated with this mod entirely. The Encounter(nor Illustrious) have this characteristic, and rely solely on the bearing adjustment for chatter control, and are not subject to the benefits of the advantages that are present in my HiFi mod in this regard.
Possible large edge for the Modded Silver here.
Counterweight. The counterweight on the Encounter is the same as on the standard Silver arm. This has been tested by me, as I mentioned earlier. The standard counterweight is easily bettered by the Heavyweight, which in turn is easily bettered by my hanging counterweight. No contest here. Definite edge for the modded Silver.
Wiring, from what I can tell, is the same on both arms. Adequate, but nothing exotic. This should be a tie.
Baseplate and mounting. The Silver has the Rega baseplate, and the Encounter has the new OL Baseplate. I like the looks of the new OL baseplate better, but I don't know whether it sounds any better or not. This is an unknown.
To sum up, in my opinion, the main reason why the Encounter is considered an improvement over the standard Silver arm is the increase in lateral mass provided by the large bearing housing on the Encounter. Users and reviewers of the Encounter are hearing the benefits of what I've been saying for over a year now. They've never heard or used my HiFi mod, so they are extolling the virtues of the "more controlled, better bass, dynamics,detail, and tonality," sound of the Encounter, without actually realizing what is causing the improvements they are hearing. I do realize what is causing the improvements. So since I think this is the case, and from my estimation and calculations my modded Silver has a better designed lateral mass implementation with greater control, I predict that my modded Silver will have a greater improvment in this area. Additionally, my hanging counterweight will be a definite improvement over the standard one on the Encounter. My guess is that these 2 major factors will exceed any of the benefits that may be normally afforded to the Encounter, when both arms are in their standard configurations.
I think that most of this also will apply to the comparison with the Illustrious, although the Illustrious has better wiring, and that could complicate matters. But the basic design of the Encounter and the Illustrious is extremely similar, and if I can beat the Encounter like I think I can, I'll have a real shot at the Illustrious.
So, those are my pre-judgments on this matchup. We'll see soon how accurate these thoughts are.
By the way, I like your "Silver Bullet" moniker for my modded Silver tonearm. The name fits well, in several respects.