I have been lurking in here for a while and I do wish to comment on the above list; but first let me show you what I am using and with the why.
Here is what I have sleaved up (and I will only discuss things in packages).
4 x AEther Vial -- This is an auto include as most of us know.
2 x Dismember -- Removal is huge and I added these after my last event where I found Standstill simply did not provide me with answers to onboard issues. Yes the life loss can be gross; but eating 4 pain 1-2 times far outweighs the consequences of repeating beatings from my opponents beatsticks. If nothing else, I would seriously suggest at least having 2-3 in your SB.
3 x Daze
4 x Force of Will
2 x Spell Pierce
2 x Spell Snare -- The control package is basically some 11 cards if you don't count the +2 Dismember above. Daze could easily be 4 off, and spell pierce/spell snare have their specific relavance depending on your meta. Overall I see no issue with what your running.
4 x Silvergill Adept -- This card draw is required.
4 x Cursecatcher -- Adds to the Control package.
4 x Coralhelm Commander -- Some guys run 3 off, I like 4; Flying gets the job done for me.
4 x Lord of Atlantis -- I see this as an auto include.
3 x Merrow Reejerey -- Some guys run 4 off and some use Merfolk Soveriegn; I think 3-4 of these is about right.
2 x Phantasmal Image -- I see you have 3 here and I respect that option. I needed a creature slot and I have seen these as dead weight if your hand is S-Adept, P-Image, land and control, etc. Thus I only run the 2; but he can do some insane things and should not ever be under-estimated (copying BoB is one of my favored moves, then remove their BoB with Dismember, and continue to gain momentum as the game progresses -- Yes FoW becomes a risk; but the games is generall over that much faster)
2 x Kira, Great Glass-Spinner -- For my Meta I need her Main Deck and she is something that you might consider as well.
Land
13 x Island
4 x Mutavault
4 x Wasteland -- 20 land didnn't cut it for me, 22 was too many, and even adding 1x Mishra's Factory simply did not work out as well as simply adding 1 more Island.
Sideboard
2 x Relic of Progenitus
1 x Tormod's Crypt -- It is a GY hate package and it works in my area, 3x Crypt works too, same goes for Surgical Extractions, etc; but you best have something to deal with reanimator's, dredge, and decks that use Grim Lavamancer, or Tombstalker, etc.
2 x Umezawa's Jitte -- Helps to level the playing field vs some aggro builds such as Goblins and Zoo, note that I said helps, as those can still be a tough to even match up.
2 x Back to Basics -- I don't have Stifle (wish I did) and I need something to help pooch the greedy mana base decks. It works but it will be swapped out when I get the Stifles.
2 x Blue Elemental Blast -- Sometimes I wish I had more of these (and Sower might be leaving) but vs anything with red you want these. RUG Counterbalance is a tough match so these help a little (for me at least).
2 x Llawan, Cephalid Empress -- I like this, and it has saved me vs U/W control, etc as a lot them are using Spellstutter Sprites, Delver of Secrets, etc as their main creatures to beat your face in. It also helps in the mirror; but you better know how to play around it as well, since you will probably see it being used against you.
2 x Sower of Temptation -- I find here cost a little high and might switch to Threads of Disloyalty as it can often hit enough stuff to save you. More Dismember and/or Control cards might not hurt either. I still like this card; but it is slow for the deck overall.
2 x Submerge -- I don't leave home without it.
** There are plenty of other cards to consider; but my main point is that right now I think that your deck would do better if you dropped the Standstill's for Dismember outright.
Blade Package In regard to a 4-5 card SFM-blade package I don't like it. It will force you to relook at the mana base and open you to other forms of hate, etc. I have found that the more I delute Mono-Blue-Merfolk to other colours, the worse it gets in the long run. I don't think that the Blade package will even to better enough match-ups to even make it worth while after you factor in the delution factor etc.
Snapcaster Mage I have also seen some guys running Snapcaster Mage; but it is tough to use Snappy to target a FoW, and paying 2+ for a Daze, Spell Pierce, Spell Snare is a bit over the top in my oppinion. I do not think that I would delute my Merfolk base any more than say 3-4 cards and right now I am finding P-Image and Kira to be stronger than Snappy.
Thanks for reading, and sorry if saturated anyone or overstated the obvious as I didn't go back and read the last few pages.