See Text and Running across Ice is a DC 10 balance check, not a DC 10+anything. So you are basically asserting that most characters have a 3-7 bonus to reflex saves at level 1, which is... odd.
Your mistake is ten times worse. It's not a Reflex Save, it's a Balance Check and the DC literally is +5~+12 depending on the terrain it's cast on.
I know you can't read, but this is ridiculous.
1) I specifically called it a balance check.
I'm asserting that characters would need a 3-7 reflex save bonus (not from dex) before the DC could even possibly be considered mathematically equivalent to 11+mod, which is what you said. Since they don't have that, your statement is obviously false.
2) The check for running across Ice is DC 10. The check for running across a
narrow severely slippery surface is +5 over what it already was, which was zero, because if they were already running over something that required a balance check then your spell isn't even doing anything but add +5 to the check they already had to make. In either case, you are completely wrong and you are making up bullshit. Cite an actual rule for this balance check, or shut the fuck up.
Also it appears you have no idea of the importance of a Balance Check. While Entangle caps out at can't move away, -2 att, and -4 Dex, or at worst only imposes a 1/2 penalty to Speed. And none of your melee-based allies can safely enter the area until you buy them some Spellguard Rings and by the time you can afford those entangle is pretty useless.
I understand perfectly the importance of a Balance check, it's just that regardless of whether the enemy makes or misses the balance check, you will never get an action when they are flat footed. Entangle lets you attack enemies while they are rooted for a minute. It doesn't even matter what their AC is.
Ice Slick on the other hand forces a Balance Check, these have to be redone every time you take damage or attempt to offset your 1/2 Speed penalty like Running or Charging and unless you have 5 Ranks, and virtually no creature does and hell even DM/PC builds often skip it, the very act of making the Check makes you Flat-Footed. FF is a huge debuff, you lose Dex-to-AC, negates several Class Features, prevents a creature from making AoOs meaning you can safely cast Spells even if you happen to be standing next to them and no creature can use an Immediate Action while FF. FF is also one of the triggering requirements for Precision Damage setting up the abuse of Iaijitsu Focus. And remember, we're literally just talking about having to make the Check so far, failure has it's own effects.
Let me describe what actually happens:
1) You the cleric cast Ice Slick.
2) The enemy has to make a Balance check. They either make the check, or miss it. In either case, the DC is much lower than the save for entangle, or even a Cleric spell. Much less Grease which forces a Ref save and a balance check.
3a) If they make the check, the walk off the Ice Slick because anywhere on the iceslick is within 10ft of not being on the iceslick, and are no longer balancing, and are not flat footed. You cast your spell, and all it did was make them avoid an area and spend a move action leaving it.
3b) They fail the check, and fall over. They are now prone, but not balancing anymore, so they are not flatfooted. They also get a +4 bonus against ranged attacks. Sure hope your team wasn't going to use those against the people that you were battlefield controlling, because if they acted after you and the enemy they are getting -4 to ranged attacks for a turn.
4) It is your turn again, the Ice Slick disappears, so who cares if you can walk on it or not, because its fucking gone, so you can walk up to be in position to AoO them as they stand up, and they can stand up, or use immediate actions, or whatever, because the ice slick is gone.
Basically, you never get to attack anyone who is flatfooted ever, so who cares.
tl;dr: Entangle holds the people still, Ice Slick does too and additionally negates an entire Action Type and it improves to-hit & damage and can set up extra attacks and it a hell of a lot more party friendly. So yes I raised Zug no matter your very subjective and poor opinion on the matter is.
Except for the part where Ice Slick never actually provides you with the benefits of the enemy being flat-footed, hurts you if they go prone, and is a DC 10 balance check that is way easier than a saving throw for most level 1 enemies, and if they pass it, they aren't even flat footed at the end of their turn because they just walk off the effect. And the effect lasts one round, instead of 10, and is therefore a "raise" only by the idiotic standards of people who make up random +12 to balance checks out of their ass, and still don't understand the durations of their spells, or how walking out of the effect works.