I just spent the past hour and a half thieving that damn phoenix only getting 702 feathers in that time. I also get strings where the [cabbage] will catch me for about 25-40 times in a row and on average I'll fail about 50 times a trip with gloves of silence etc. What level do you guys advice to get for this little [cabbage] as he's wearing on my very very short fuse atm.

Not really worth it to train thieving just to thieve feathers. From my experience I could tell no difference between 70 thieve and 90 thieve in getting feathers, so I don't really know.

I may be totally wrong here but I thought the best reported (realistic) rates were 500 feathers an hour?

Which would make an hour n half 750 feathers, thus not far off ur outcome.

I've been getting ~650 feathers in one larupia pouch (49 mins)

I'm thinking Ardy Cape 3/4 makes the difference here, since gloves havent been degrading - so assuming they're not working.