First, let me say long-story-short, I bought a PS3 to play Skyrim a few months ago, and it's been a WONDERFUL experience (aside from the bugs that ALL versions have...) and I'm glad I played this way-after the framerate issue was current!
Now, having said that, and having read up on that previous issue AND the current issue with the expansions - I have a very modest suggestion that might help.
I know, I'm not a programmer - so I'm not sure how much this will help, but I'm going to suggest it anyways.
OK - the big problem it sounds like are that when the game-save files get about 14+ meg is when the PS3 has stuttering problems - right? From the sounds of it, it sounds like Dawnguard/Hearthfire are having these problems.
Well, instead of trying to make it work with a 15 meg file - how about you guys reduce the file-size of the save-file instead, and I have (hopefully) JUST the idea to help you achieve that!
How you can reduce file-size is simply turning off/switching around the parameters that flags oh-so-many of those wonderful dungeons to be safe-zones after you clear them. Do they REALLY need to be safe-zones?
I cannot express annoyance enough at how many times I re-visit a dungeon, JUST to discover a month later it's STILL cleared and find out later that it never respawns. Do you know HOW many of the major Dwemer dungeons that respawn? FOUR!
Respawning Dwemer dungeons:
Mizinchaleft,
Rolbithar,
Alftand
Nichuand-zel...
Also includes a plethora of tiny places like Reachwind Eyrie, 2 of the tiny houses in Blackreach, and Kagrenzel (which is just a pit that drops you into a small cave lake).
Safe-zone non-respawning Dwemer Dungeons:
Avanchnzel
Bthardamz
Irkngthand
Mzulft
Almost ALL of internal houses in Blackreach (seems to record loot taken, but respawns enemies)
...and the Dwemer Museum/Calcelmo's Laboratory. >_<
I mean, seriously, that's over HALF the Dwemer Dungeons/related locations - and some of the COOLER ones I might add!
I mean, do we REALLY need to permanently record what was taken from the Dwemer Museum? Must we not respawn items in there if we take them?
The above list is just composed of Dwemer dungeons... this list is not including all the countless towers, forts, Drougr ruins, Falmer Caves, ships and what-not that do not respawn either.
I mean - WHY would those need to be saved as safe-houses? Is it REALLY important to have Irkngthand recorded so that nobody tries to play it again and all they can do is walk through a vast empty place? Can you NOT flag it just like you did with Mzinchaleft where all the puzzles are unlocked, but the enemies/loot respawn? How much of your save data can you get back if you do NOT record every single item/chest in those dungeons that, chances are, NEVER get touched again?
And, yes, it records what is in those perma-cleared dungeons. I went into Calcelmo's Laboratory and discovered an item I left in there a month ago in one of the chests.
So, how would it work for dungeons with - say - dragon priests in them? As I said, just like Mzinchaleft. Maybe you can code it so that, once cleared, it just tosses in a generic Dragon Priest in there?
How much file-reduction could you get if you just TURN those never-respawning dungeons off?
Again, I'm not tech-savy - but it's an honest question. Have you considered it Bethesda? Maybe this - along with future expansions - you can save a crap-ton of memory by just flagging dungeons as respawnable.