Nice one!
I've been running a HLR15 side by side with a EB351-5/15 recently. Both machines are great, with a couple of key differences.
The EB351-5/15 certainly has more torque and slightly better battery performance. I've found the Rupes tends to slow down as the battery nears its end. Whereas the ShineMate will simply stop, which prompts a battery change straightaway rather than a degradation in cutting performance. I also think what ShineMate delivered for the price makes them very hard to look past. And from what I was told last week, it sounds like the ShineMate stuff is very, very reliable compared to the Italian reliability quirks.
The Rupes on the other hand is butter smooth and much quieter running, lacking that typical DA grind, to the point where you don't necessarily need hearing protection. I also like how the design and battery placement gives you an option as to how you hold it, the ShineMate really needs to be held by the battery, which I actually prefer but sometimes its nice to have the option. Both of those aspects as well as the lighter mass add up to less fatigue. Performance wise, the Rupes has much higher RPM headroom, the ShineMate feels like it needs another higher speed setting. And as you mentioned, the feel of the Rupes in your hands is second to none.
I was actually going to sell off my ShineMates, but I think I like having both. The ShineMate is probably better for heavy duty cutting because of the torque, and the lowest speed setting is ideal for wax/sealant application. The Rupes though is very nice to finish with.