This I would say is pretty decent but the Crit is too low.
Through my playing of SMN, I noticed there are what I would describe as noticeable thresholds of Crit. They occur at 520+, 530+ then 545+. The lowest amount I would personally ever recommend is 520 crit.
http://ffxiv.ariyala.com/QH6R - This build would be a nice balance between my recommendation and your build.
http://ffxiv.ariyala.com/QH6T - Switching the bracelet for the poetics here gives you a bigger Crit ceiling. Would be good to test out either of these.
For any build however, if you find yourself over ACC by a decent amount, it's time to evaluate a crafted item and how much Crit / Det you can gain when you sub out INT if ACC isn't an issue.
This answers this:
The reason I don't consider the Demon shoes to be BiS despite the very nice stats, is because you will have ACC problems or your Spell speed is too low in any build you can make that pushes the your stats to the limit.
Well let's play with the theorectical stat weights at the moment. 1 Int is equal to about 3.5 DET. Which would mean 5 Int is equal to 17.5 DET. From in-game testing however I feel its slightly lower then that. I think 5 INT is closer to what 15 DET will give you when you consider the pet as well. I think and always consider my builds in a 1 INT = 3 DET roughly.
INT to MD atm is roughly 6.9INT = 1 MD or 20-24 DET
I explained my thresholds of crit and what I felt was valuable numbers as of 2.55. ACC above all else is the first stat you must cap. You CAN survive at 1 below the cap and do very well as I have proven this in SCOB. If you ever felt like 534 ACC (535 needed for T13 for pet) was cutting it too close you can make sure you position your pet on the rear instead of the flank. Pet position also is subject to the ACC required in my testing thus Ifrit / Garuda attacking a target from the rear is always going to be 100% even if it's one below the cap. When T9, was in progression, 491 was considered the 100% pet ACC however, I ran 490 ACC and picked up 30+ DET in the process and Garuda I noticed only missed 1 or 2 times per run during the final phase when the boss actually faced Garuda during the Supernovas. These misses in that small window however were largely outweighed by the damage I gained from that 30+ DET, thus making the 1 below ACC viable.
The problem with Ifrit however is that when a fight begins, you are required to start directly south in line with a target to pre-position Ifrit for this without having to move him. A boss like Imdugud for example that can shift his body in one skill to a point where Ifrit can jump from attacking the rear to now attacking the flank or even the front, is another thing to consider when evaluating this. Bahamut Prime atm, does not make any of these sudden shifts.
Sidenote: Bio 2, Bio and I believe ShadowFlare as well apply regardless of ACC out of the ACN skills, so fights like T11 that require consistent movement and a possibility to wind up in front of the boss to dodge Nerve Gas, these skills can be applied from directly in front even if you don't meet the front cap.
Now when I feel two builds are TOO close to really call from my personal use in-game with parser included, I use PuroStriders SMN calculator to see more in depth and compare the two. Granted it is outdated now with the slight changes that have occurred to SMN since Nov, but it still feels fairly accurate as to when I feel something is too close of a call, the calculator shows me the same.
PS: Again I would not use the calculator as a forefront for making a build. It is imperative you do constant testing in-game with parser above ALL ELSE including the current documented Stat weights each patch. At 2.4, I felt the stat weight shifted to the point where Crit / DET influenced your damage overall much more then before 2.4 for example, while the stat weights on Ariyala and calculator were both still showing data from previous patches.