@Sigtrygg, I really do appreciate these discussions, just so you know!
I've actually examined the fuel issue in detail, and while I had not thought much about the armor issue, I will say that:
1) I believe these changes were deliberate, as I will show below, but:
2) They are easily added back if you are so inclined, though I think this analysis will show why they were not.
By the way, re. your comment about using the LBBs: did you not mean High Guard (HG)? MegaT clearly used HG as the base for its starship rules.
1) Fuel: It may be surprising the degree to which the DG crew tried to maintain compatibility between HG and MegaT. The 3 fusion power plants in MegaT for TL 10/13/15 assuming highest efficiency (3x MW at 14+ kl) are almost exactly the same volume as TL 10/13/15 HG power plants per 250 MW (MegaT)/1 EP (HG) and 100 D-tons of hull (i.e. 3/2/1 D-tons). The only difference is fuel consumption: MegaT plants use 6.7x that of HG plants. So your point about scaling is subtle: MegaT plants are producing the same power as HG plants, just using much less fuel. Further, MegaT plants are carefully balanced to consume the same amount of fuel per MW regardless of size or TL. Therefore, it is easy to restore HG fuel consumption: multiply MegaT fusion plant fuel consumption by 0.15 (which is exact, per my calculations). You must then restore HG jump fuel requirements of hull %age = 10% x jump number.
But I think my analysis explains why this was not done: HG fusion plants are nearly 7x as fuel efficient as Striker/MegaT plants. Should this apply only to spacecraft, or to everything? Traveller5 seems to be using the latter, as its fusion and Fusion+ rules seem crazy lenient, and so this is a valid choice. I prefer that, in MegaT, as TL increases fuels cells start becoming very competitive with fusion. So I think the MegaT decisions are fine, but it is easy to reset back to HG via that simple factor, which would then more easily allow higher Agility like HG did.
2) Armor: I think MegaT dropped Armor volume deliberately. Why? Because its vehicle system makes no mention at all of dimensions, which are required for the Striker armor rules. But also, HG HAD armor volume rules, and they were not used. I think it is just as valid to assume that armor adds exterior volume than it takes up interior. But again, this is easily fixed. The following formula replicates HG armor volume with MegaT factors:
MegaT armor %age of hull = [10x (1+[MegaT armor factor-40]/3) x MegaT Armor Type Weight Mod]%
Again, this will come close to replicating HG armor volumes, not necessarily Striker. For vehicles, you can just use Striker as you suggested.
I'll give you two bonus HG adjustments, one which I use and one I don't.
3) Bridge: HG required a bridge to be 2% of the hull, 20 D-tons minimum. MegaT control panels don't come close to replicating this volume, so MegaT ships RAW have more space. I added back the concept of a Duty Station (which I have since seen in other products), which takes up 2 D-tons like a small stateroom. A minimum of 10 are required for a starship, or else equal to the number of non-frozen crew, so this creates a more fluid bridge size than HG.
4) Computer: HG computers were GINORMOUS! The thinking may have been that a HG computer includes lots of stuff that is excplicit in MegaT, like life support, comms, sensors, and control panels. So one approach is to require HG computer volumes and costs, but use them as a shopping allowance for other equipment. I don't see a reason to do this, and I suspect MegaT computers + other stuff take up less volume than HG computers did on average.
I'll close by noting that the strong reaction that many players had to these changes is a flaw of MegaT that, in my view, is worse than the errata: MegaT was clearly not playtested sufficiently. More and better playtesting would have caught more errata, found unclear rules (like combat), and highlighted unexpected changes like those above. I've addressed all of these in my rewrite of the rules, but it really is too bad this wasn't done at the time.
