I have the Zephyr Typhoon...used the 4 watt Lighting Ever LED's but they stand about 3/16" proud of the hood surface. As long as you replace both bulbs, it's not really all that noticeable or disagreeable. The LED's are so much better than replacing halogens every 30 days (or so it seems).

As far as grease escaping thru the opening...that's a non-issue, really. The original halogen bulbs certainly don't form a vapor proof seal so it wouldn't make sense to expect replacement bulbs to block vapors either.

To date, there doesn't appear to be a standard size for replacement GU10 LED's. Your best bet is to measure the original halogens and try to find an LED that is the same height AND puts out an acceptable amount of light. I was very pleased with the light amount/ quality of the Lighting Ever LED's & was aware of the variations in the height of the different brands of bulbs so decided to accept a less than perfectly flush fit.