Switching between discs.

I am wanting to run through the offline quests in ULT mode to finally finish them. I never finished them on anything other than Vhard. Although I play using Alerons Enchanced disc, I don't expect to be able to beat Ruins on my own(especially in any sort of reasonable amount of time). If I were to switch back to a GDrom version of the game and play through on the original game stats, would I face any problems? I have upgrades gear and such using my photon points online, would this cause any issues? Also if I were to attempt the quests offline on my own with the enhanced disc, does anything think I stand a chance at lvl 135 as a Hunewearl?

Offline mode is easier than online, so that's always a plus. If you used materials to reach the new stat caps, returning to an unpatched disc will reset your stats to their original limits, and then you'll have to raise them again when you switch back. The only way to prevent the reversion is to never go back. You'll also lose the ability to equip the items that you can't use without the EP, which is a problem if you rely on some of those items.

One benefit of playing the offline quests with the new EP disc is that you get PSU-style automatic NPC revival, so even if most of the NPCs get killed, you won't fail. In that respect, some quests are actually easier with the EP disc, e.g. trying to keep MOME alive through the Dal Ra Lie fight. As long as you have something basic like an Imperial Pick with 30% for each area from Garon's Shop, Ludicrous mode shouldn't pose a problem when you use S/D/J/Z on everything.