They were published in a captains log and are written by SVC so they are probably as offical as your going to get till X1R formally comes out. As far as cheese, it's not so bad since overall it makes ships more expensive.
In your opinion, what "works" in SFC for the XP refits? I'm thinking the XPR and conversion of PH2 to PH1 is the only thing that "works" and isn't ridiculous.
phaser conversion, drone rack conversion, plasma conversion (albit with different letters here), XPR, XBTTY, hydran fighter conversion all work. Bear in mind that 2 BPV per APR doesn't sound like much in and of itself but it adds up
FAST. The Completely XP'd ISC CC comes up to being just 5-6 points short of the 315 point CCX for example. As with all things, some ships benifit more than others. Note than since SFC lacks the M-Torp, and we are using R's for them, we'd need to bump up the XP cost for S to M somewhat to reflect that.
And for those people looking at their favriote war cruiser to apply the big refits to,
can't.
Using the Kzinti DDL as a example; applying the XP refit(s) to it gets it 2 more power, and changes the 2 B racks to two GX racks. can install XBattery but there is rarely a point to in SFC. Base cost: 114. Final after XP cost: somewhere in the area of 138 depending on what you do to it.
Using a popular Fed ship, CLC:
Base price: 143
XP Price: around 192
+4 Power, +8 Btty, Ph3->Ph1, G racks to Gx racks.