The primary beauty of the LBB2.77 100 ton standard hull J4XBoat design is that it's both CHEAP and TL=10, yet still gets the job done.
The Express Tender is (in my opinion) "too big" at 1000 tons displacement and ought to have been built as an 800 ton starship (also @ TL=10).
It's hard to overstate just how "unfairly useful" it is to have such high performance starships at such low tech levels when it comes to industrial sources capable of supplying the necessary construction, maintenance, parts and spares from a logistics standpoint. By keeping the tech level "low" for starships (merely "Average Imperial"), this allows the IISS to contract MUCH more widely and have far more secure supply lines able to keep the Express Network operational.
Pretty much ALL options to "upgrade the network" are going to require a tech level bump in some form or fashion in order to make any improvements. Although, it is theoretically possible to create a LBB2.77 custom hull J6XBoat design that is almost as cheap but requires TL=12 for a model/6 computer and L-Hyd Drop Tanks (LBB5.79), that's about as far as you can push things with LBB2 (which honestly, is pretty darn far!).
The reason to install maneuver drives into XBoats would be to reduce their dependency upon Tenders for recovery, refueling, refurbish/replenish and relaunch operations. Personally speaking, I'm thinking that doing this would be a First Principles Mistake™ ... mainly because the role of launch/recovery AND mobile turret is better done through use of small craft capable of docking with and "towing" XBoats through normal space to/from Tenders. Having rapid reaction fighters that use the Tender as a mothership and coordinate with the Tender for recovery and relaunch of XBoats, in addition to providing mobile screening and Combat Space Patrol defensive perimeter protection would be the better way to go.
You'll still want to have Scout/Couriers interfacing with the Tenders as "runabouts" for fuel, delivery of consumables supplies and personnel rotations, etc. in addition to their courier dispatch duties (when a Type-S breaks out of jump, it rotates into "runabout" duty while the current "runabout" assignment gets updated with current courier data and dispatched to jump, allowing Type-S crews to rotate through Tender servicing ops to get their flight hours in and keep their normal space skills practiced).
Ideally speaking, I'd want to do a top to bottom "refactoring" review of Express Network craft design and operations ... but I'm just weird that way.
![Kissing face with closed eyes :kissing_closed_eyes: 😚](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f61a.png)