-spd on Kliff

I would really recommend against it for a few good reasons unless you only want him to avoid doubles.

1. This really hinders him running or having Flash support. He's one of those characters I think benefits having his special cooldown speed up more than others. There isn't any other way for him to even dream of getting this effect on people.

2. His player phase will be hindered greatly even on neutral especially if you want to keep chill speed. Him with chill speed active along with his tome will even double Karla. Therefore, adding on QR would kind of be a waste for his potential. If using him only outside of arena I think it may be better because of those inflated stats you mention.

3. After running some calcs on him I realized that a speed bane actually gives him the worst MU spread out of all of the banes you could get. This is because you fail to kill strong sword lords (his main thing he NEEDS to kill) and fast mages become a bigger problem) If you buff up his speed by 6 consistently it won't be a problem. You also tend to struggle against people you can't activate your tome on even more as you have a huge potential of being doubles by them and you don't get the boost to defenses. It sounds like a bane may work if you plan to buff it with speed wave but even then his potential becomes limited.
3.He can actually player phase blue and red armored units before they even get their special off. To beat B!Hector with DD3, you need to have a res ploy, +6 buff, neutral attack, and your weapon activate. The fact that he can do this is scary. Same thing beats Nowi ofc. And you don't even need all of those factors to beat L!Tiki.

As for a B slot whenever I run the calcs his best B slot becomes Guard fairly easily. Though if you want to play around a team keeping Chill Speed isn't a bad idea. He starts to destroy some greens in the process and Armored units find it hard to face off against him. His speed if you run either a +6 buff or a debuff becomes unmatched outside of the enemies having some kind of buff so I think it should be entirely left alone and he has no NEED to put a boon there. The calcs tell me it's over kill.

With all this said and all of his MU's in including some of the other less common ones, I finally have figured out his best ivs when including buffs. +Res/+Def -HP. He's able to kill the most and strongest opponents with this iv spread, and survive the best. That's because he is either able to kill someone before their special activates, or guard blocks it off entirely. However, -Atk is a good choice for a second bane if you don't have a -HP one.