You really can't say the second is fine as it is without justifying yourself. See:
http://www.chambersharrap.co.uk/chambers/features...py/main?query=wise
http://www.m-w.com/dictionary/wise
http://dictionary.reference.com/browse/wise
http://en.wiktionary.org/wiki/wise vs
http://en.wiktionary.org/wiki/-wise
As for the comma, the phrases on either side of it are independent clauses. The comma has many functions but none of them are separating clauses like this; syntactically you may just as well use no punctuation at all, although the comma does deceptively add a little oral intonation similar to the correct options.
Of course "ensure" is also a verb, but as you say, "insure" has a different meaning
I should hold my hands up here and point out that I'm not purposefully being a grammar bitch, but it might as well be right if it can
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