..are none.
Recently I decided to test what the exact effects of the GP furnishings are. Generally it's accepted that it's a +1 to skill at 9-50 energy, but nobody has been able to give any evidence that it is indeed only +1 skill at 51-100 or at 100+, since that'd involve taking a craft to 88+, spending 150,000 GPs on the furnishing, then leveling another craft up to at least 77 to get the main craft to delevel to 83 to test the skill by attempting level 100 synths in the main craft. However, I figured it was worth checking out, cause if I could get +2 skill at 101+ energy, I'd have the potential to make some excellent money by breaking tier on certain cursed items, and leveled my Alchemy to 88 and got myself the GP furnishing, with the sole purpose of deleveling it afterwards to run some tests.
Test 1: Confirm that the furnishing does indeed give +1 skill.
I took out my GP furnishing when I deleveled to 84 Alchemy and attempted to synth a Pro Ether (level 100 Alchemy synth). I was unable to attempt. I then put the furnishing back in my moghouse and attempted the synth again, and promptly failed. Since this is generally accepted as fact already, I didn't bother taking SSs of these results (actually I did SS them, they're just on my laptop and I'm lazy, maybe I'll add them later).
Test 2: Check to see if any additional skill is gained by reaching higher levels of the corresponding energy levels while retaining Moghancement: (Craft).
This is a screenshot of my energy level at Overwhelming energy (101+) with Moghancement: Alchemy, as well as a SS of my level 83 Alchemy:
http://img252.imageshack.us/img252/1811/synth0wc8.jpg
http://img518.imageshack.us/img518/5038/synth1dk9.jpg
I would now attempt to synthesis a Pro Ether (100 Alchemy synth, 17 levels over my native skill):
http://img518.imageshack.us/img518/2559/synth2zg3.jpg
I am unsuccessful in being able to attempt the synth:
http://img111.imageshack.us/img111/7403/synth3pu3.jpg
So there you have it, folks. A good 2-3mil and a couple months of my time wasted! But now it's known for sure: Furnishing gives +1 skill, and +1 skill only, regardless of energy.