I have added up to 5% DW to my vape, but I can only tolerate 10% PG before I get unfortunate effects. You may not (probably will not) need that much, even, but you can safely go to 5% if you want. It may be worth a try although you are getting plenty of good suggestions, so there is always that.
Notable temp difference and for me, it did not adversely affect flavor in the slightest, it may have improved it slightly but I am PG sensitive, so.... You may find it different than just a straight higher PG juice.
Anna