In Federation Commander, the "Constitution without aft phasers" is included among the range of Middle Years ships published in Briefing #2 and Booster #91; that era is considered a separate setting in FC to the Main Era (General War) ships seemingly being used as the basis for those in ACTA:SF.
Which, I guess, could in theory make it easier for Mongoose to consider doing a Middle Years book (perhaps incorporating the "Franz Joseph" designs?) at some later date... but I suspect that won't be in the table for quite some time to come, if ever.
But one thing I should probably say is that regardless of era, this is still the Star Fleet Universe; one way or antoher, there is always going to be something which makes it that bit different from the Paramount/CBS Franchise material. It would be a shame to lose out on all of the great things it is by getting tied up by what it, by its very nature, cannot be.
Which, I guess, could in theory make it easier for Mongoose to consider doing a Middle Years book (perhaps incorporating the "Franz Joseph" designs?) at some later date... but I suspect that won't be in the table for quite some time to come, if ever.
But one thing I should probably say is that regardless of era, this is still the Star Fleet Universe; one way or antoher, there is always going to be something which makes it that bit different from the Paramount/CBS Franchise material. It would be a shame to lose out on all of the great things it is by getting tied up by what it, by its very nature, cannot be.