Fixing IE bugs: always a good idea?

Internet Explorer improved a lot in the last 3 years and since IE 10 has become a fairly decent browser with good performances. But, even with these improvements, web developers still have to:

1. deal with older versions, in particular IE8 or even IE7;
2. work around bugs the IE drags since forever, like the unimplemented document.evaluate, or oninput event that isn't fired on deletion or on contentEditable elements.

I was asking myself what's an "acceptable" limit for those workarounds. For example, IE<9 change event doesn't bubble up: but since it supports focusin and focusout, which do bubble, it can be fixed with a couple of event listeners.

It's also well known that IE<9 doesn't handle the innerHTML property on <select> elements properly, so we can redefine the property (IE8 only):

(function() {
    var re = /^<SELECT(?: [\w:]+=(?:\S+|'[^']*'|"[^"]*"))*>/,
        div = document.createElement("div");
    Object.defineProperty(HTMLSelectElement.prototype, "innerHTML", {get: function() {
        var out = this.outerHTML, m = out.match(re);
        return m ? out.slice(m[0].length, -9) : "";
    }, set: function(v) {
        this.innerText = "";
        if (v = String(v)) {
            div.innerHTML = "<select>" + v + "</select>";
            var s = div.firstChild;
            while (s.firstChild) this.appendChild(s.firstChild);
        }
    }});
})();

But IE - even IE11! - still doesn't allow to dynamically set the value property of a <select> element, so (IE8-11):

Object.defineProperty(HTMLSelectElement.prototype, "value", {get: function() {
    var opt = this.selectedIndex >= 0 ? this.options[this.selectedIndex] : null;
    return opt ? opt.value : "";
}, set: function(val) {
    val = String(val);
    var ops = this.options, i = ops.length;
    while (i--) if (ops[i].value === val) break;
    this.selectedIndex = i;
}});

These work quite well, maybe a bit slower but just in a resticted case: HTMLSelectElements. And they rarely can represent a performance issue.

But since I'm changing some basic DOM properties, I was wondering if there could be any problems that I'm not sighting. Does anyone have an idea?