Hi guys,
After some time I have had the chance of testing myself both options. Joyful time, by the way...
Short review: Both options are awesome for silent recording. If you have already found "your tone" using a very specific tube amp, then go for the torpedo without any kind of doubt, but if you are in the "chase" of it or you need many different tones, then buy the Kemper (you will save A LOT of money).
Long review:
Two notes torpedo (live in my case) is a very accurate way of recording your tone in silent mode (headphones only if needed). It really allows you to find the sweet spot of your amp and record it without the big noise. For some amps, like ENGL Powerball, was pretty easy... Just setting the master to one o'clock (60% or so) and you get that, bluesy sound for the channel 2 and metal fury on channels 3 and 4. Unfortunately my experience with the Mesa Boogie Dual rectifier was not so good. This amp is a really powerful monster, so when you set the master volume higher than the 20-25% the Torpedo starts to sound pretty bad (it was not my unit, because I tested two and both had the very same problem). Two notes torpedo live is designed for 100W RMS and I confirmed with a technical guy that this amp delivers more than 160W RMS... that's a lot... Just to much for the Torpedo. However, I was still able of getting the kind of tone from the dual rectifier, with short options of tweaking around.
Kemper is a very different option. I have spent some time looking for the right rigs, but now I have at least 3-4 sounds that are pretty impressive. I can't imagine how they could sound better (Bogner Shiva, Marshall JCM 800 and Mesa Boogie Dual rectifier). Unlike other digital solutions (Axe FX, Eleven Rack, POD HD, etc), Kemper does not require a lot of tweaking... Indeed, you find the right sound or you don't... Once you've got it you just tweak the reverb or some basic eq and you are there... Axe FX lovers won't probably like Kemper, I guess.
In my case, Kemper is a better, more affordable and easy to maintain/improve solution. I get what I need and much more, additionally I do not care about changing tubes or carry heavy stuff (kemper is far more lighter than any tube head plus the torpedo plus the effects...).
Both options sound pretty real, pretty accurate, organic and natural. I can't imagine anyone able to distinguish between the real amp recorded and the Kemper or the Torpedo (just listening, not playing). After trying both I find that Torpedo is really suitable for those that really love just one amp and build their sound around it with pedals and so. In any other case Kemper is better IMHO.
I hope this helps for those having the same problems I had before investing quite a lot of time and money to try all the stuff on my own... However, if you have the chance, do it yourself! (no one will judge it better than you).