The main thing about the Silver that I like over the other RB250 hotrods is that the Silver has the bearings moved out to the bearing housing yoke instead of having them in the arm tube. This widens the "stance" of the bearings, and this is a much more stable arrangement for the bearings.
Regarding the other stuff on the TecnoArm
Holes drilled lowers effective mass, which is going the wrong way for the cartridge you intend to use.
Foam inside the arm is not a good thing in my opinion.
The machined headshell and counterweight are nice things.
Unbroken wiring upgrade is a good idea, but I'm not a fan of silver litz wire.
With the OL Silver, you get a better basic structure, but you still need to buy some additional things like an upgraded counterweight. It is not "the last word" in tonearms, but it is a very nice choice in the price range, especially if you plan to use a low compliance cartridge, and that it has the availability of the HiFi mod to make it a match for such cartridges. For "leading edge dynamics" it is probably one of the best setups that you can buy, regardless of price. It may lack in certain areas compared to the high-priced superarms, but is a quite competent performer in all areas. And even the superarms aren't perfect, either. At least, with this arm with the HiFi mod, it can claim state-of-the-art performance in one area(leading edge dynamics), which is more than anyone can say about any other sub-$1k tonearm. Not perfect, but nothing is, and it is a good arm for the money.