@CaesarVialpandom, I am using a ThinkPad T430 that is basically identical to a NitroPad T430 with the i7-3840QM and 16 GB of RAM. I added a full HD screen (not sure Nitrokey offers that) and a Samsung PRO SSD (the PRO is important).
I use a Windows 10 HVM for some tasks (4GB RAM, 2 VCPUs, 100GB storage), which works just fine for Visual Studio, other IDEs and dev tools, Webex/Teams/Office etc. I have added a $20 USB express card to give Windows it’s own dedicated USB controller (for the debuggers, tracers and all the other stuff you need when doing Embedded programming) and a similar priced USB-Audio interface for sound.
I run 11+ qubes concurrently and permanently, all debian-minimal based. My sys-net, sys-usb, sys-firewall etc are all happy with 200MB memory. Vault gets 250MB. Signal 400MB. Offline qubes with LibreOffice, PDF viewer, VLC etc work fine with 500MB. Thunderbird qubes needs 700MB to work well in all situations (large mail database, searching etc). And Firefox qubes need at least 1GB to not be annoying (I have set the concurrent process limit to 1 to make it less memory consuming).
With a setup like the above it is quite unlikely you run out of memory with 16GB. Hasn’t happened to me yet this year 
Things like wake/suspend, docking station just work like a charm Also I am driving a 4K external monitor with it. There are several NitroPad / T430 users in this forum here. As far as I can tell, they are all quite happy with their machines. Maybe they will comment here too.
I did also upgrade to quieter fan ($30) and exchange the Wi-Fi card (I think Nitrokey offers that as an option).
Couldn’t be happier. I just received a second T430 and are still waiting for the the other parts (display, fan, CPU, SSD, WiFi, RAM) to arrive. I am building a second identical machine. This can be done for ~ $1K. The idea is that I get R4.1 running perfectly on the second one and then switch over when it’s ready. R4.2 back to the other one etc.
That together with nightly backups means I will use this setup for a very very long time.
I understand that the t430 has a faster processor, but can it be recognized in Qubes at all (+10-15%)?
Yes, go for the quad-core i7-3840QM. The number of cores does make a very recognizable difference. This is different form the “speculative execution” topic.