the uchigatana is better than the raikiri, i was happy to get rid of that thing. "Decreases movement speed" is un-bearable, and samurai need to take advantage of any accuracy boost they can get, over time even the smallest ammount gives a larg boost to your TP gain. not to mention the DPS is higher on the uchigatana, the only time i recieved attack+10 was right before i died helping my friend on an AF quest in garliage cidatel.
Just thought I'd add my experiences for anyone curious about what weapon to use at this level.
I used the GMU for roughly three levels of experience before a friend suggested the level 56 Great Katana; the Raikiri(DMG 69, Acc+3, 437 Delay, Thunderstorms: Attack +10, and the dreaded Decreases Movement Speed), may be better. The Raikiri, on my server (Leviathan) went for 80k as opposed to the GMU's 200k, so I figured it was worth a shot. So I took it with me to my next exp parties(Level 63ish, Diremites in Aydeewha Subteranne, and later on Processionaires in Boyahda Tree)
Using both weapons equally throughout parties, and then testing it out on various mobs of ranging difficulty for a few hours solo, I can tell you that the Raikiri is actually better. The delay is the selling point of the GMU, usually. You will not even notice the difference in delay between this and the Raikiri; it seems almost exactly the same. Next, damage. I was hitting for an average 15-20 more damage per hit using the Raikiri. My accuracy seemed roughly the same as well, with +38 accuracy in gear and Madrigal from a Bard(this is nothing different from usual as I static with a Bard). Given that the added Earth damage almost never procs anyway, I have say that hands down, the Raikiri is better than this, especially if on your server, the price is lower than the GMU. Not to mention the potiential +10 extra attack you can get in Thunder weather, which kicked in a few times for me in Tree and I got numbers even higher; roughly +30 more damage in place of the 15-20. Besides... it's a sexy blue and gold color. ^^
The only drawback is, of course, the decreased movement speed. This is an annoyance for those of us who like to Meditate as we enter an area and have TP ready when we begin, but it's not -that- big a hinderance to just take it off while you're running.
Hope this helps out; the 60 range gives a variety of choices in weaponry for SAM. ^^
I have a GMU, which I upgraded for Koryukagemitsu(sp?). Belive it or not this GK has a better Attk, but not by much (I like the look and damge this does anyways ^^ . Taking this into consideration with the shorter delay over the +3 str on the Daihannya with the higher delay, I assume this will do better with more hits for more dot, but take more swings to get 100tp. However, the +3 str for the weaponskill would be nice, but without the +4 acc for Yukikaze, I wonder how often you will hit.
You can never have enough ACC. If you feel that you have plenty of ACC, and also have the 800k to purchase the GKT, then by all means, get the Daihannya. GMU is the fastest GKT in the game as of yet, and the DMG at that Lv is pretty good for the delay. It all comes down to how much moeny you are willing to put into your job. I for one always try to get the most ACC possible. As a SAM, you cant Skillchain very effectively if you can never hit. But like I said, if you think you have the ACC and are willing to pay the money, go ahead and splurge.
This great katana may be better than zanbato due to the low delay and the accuracy up... I prefer Zanbato though, just because ive been using Uchigatanas and Tachis for all my SAM job @_@;
In my opinion it all depends. I am an Elvaan SAM60/WAR30 and for me acc is more important then base dmg. Elvaan's are inherently going to hit harder then say a mithra but will miss a great deal more often as well. Therefore, you want to enhance the abilities you lack in. ultimately, the goal of a samurai is to skillchain, therefore, if you are elvaan I would suggest the GMU because its the fastest GK in the game plus the Acc bonus come together to help you build tp faster (the Attack bonus and earth damage are nice too ~.O) . However, if you are a mithra you already have a considerable advantage in DEX but lack the str of an elvaan or gelka. Therefore, you probably want to go for a GK that has the good base dmg like the zanbato or dihannya. Now on my server, ifrit, the GMU is currently 210k, the dihannya is 2mil O.O, and the zanbato +1 is 500k. Factoring in the price, I belive that the GMU is the best bang for your buck.