On the cloak:
It is an option, just like scatterpacks, that can be used at the pilot's discretion.
Now, with damage reduction and loss of seeking weapon lock-on working, the cloak is about 90 - 100% functional.
And just like all options on a ship, you shouldn't be able to do everything at once.
I'm not intimately familiar with the Roms in early-era, but I always believed the Romulan's early era complaint centers around the speed of their "bird / eagle" designs, I don't think any of the Bird / Eagle designs can even reach speed 31 on Green alert... The best (War Eagle) I think chugs along at speed 21 - 25 or so...
Once the Kestrels start coming out, then it's a different story for the Romulans, and there are little complaints about Rommies in the "hawk" era...
Early era work, needed. Cloak reduction, with a now-working cloak, not needed.
On the DN issue, we already have a sort-of "lose a restricted ship, no immediate replacement" method in the Field Marshall system. I do like opening it up (a-la LB5 with cheaper prices), and the idea that the "replacement" DN is also banned from the hex. Although, perhaps to make it easier to police, we could go with all DNs (or other restricted ships) from the banished race are banned from the hex. Although with that limit in place, the time should not be any different than if it was a single ship loss.
In the LB-5 ish restiction system, I'd ban a player from buying a restricted hull for 24 hours from the time of the initial loss...