The trick is not keeping water/dirt/ect out of the airbox --- it's keeping this stuff off the filter.
The HRC lid will deflect most incedental water from contacting the filter - the EHS lid may have a "Water Resistant" outerwears over it, but I've done water penetration tests on that material before and it leaves a bunch to be desired.
IMHO - opening the lid directly above the filter element is asking for trouble -- do what you will, but consider the fact I am only offering my experience & opinion as advice, I stand to gain no profit by your decision either direction. Choose what you will. But rest assured that there is a reason the HRC is designed as it is - and I guarantee Honda has a lot more experience under their belts than EHS in the design and R&D departments.
I had one of those airbox lids before on my 250R, and i really wasn't too impressed. I like the concept, but it cost too much money in my opinion. Money is better spent on a second airfilter and changing it mid day! I rather run an HRC lid as opposed to the EHS lid in muddy condition. I found that water WILL definately penetrate that outerwear. Actually what will happen with that lid is that water may not get through immdiately but instead, it will pool up ontop of the outerwear then come through down onto the filter, IMO a wet filter will hurt you more than a dirty or dusty filter! I agree with 86atc250r, the HRC lid will deflect most water from hitting your filter directly, some water can get into the airbox, where it will go into the drain tube. IMO a better solution than the EHS lid would be a combination of the HRC lid and a filter OuterWear. This combo will keep your filter very safe. The outerwear will deflect sand, dust, and most water away from the filter, down into the air box. I found that I had more power with a filter outerwear and a cut airbox, as opposed to running the EHS lid on my 250R, I have a feeling this would probably hold true with my 450R as well. The EHS lid would work ok in the sand dunes though where water is not an issue, but again, you are much better off with running an open airbox with an outerwear on your filter instead!
Yep - that would be my suggestion - the outerwear directy on the filter keeps the big debris from packing the filter, the oil catches the small stuff, the lid deflects water, the drain does it's job and everything works as it should
I generally run the filter by itself unless I'm in the dunes - the outerwears works great for preventing sand packing of the filter. I'll also likely run a filter outerwears at this year's 12hrs of America race - last year at about the 1/2 way point our filter was pretty heavily packed with dirt & although it wasn't yet causing any performance problems, we took the time to change it just in case.
When you run an outerwears on the filter, try to be careful & get as little filter oil on it as possible - that allows the dirt/sand caught by the outerwears to fall off and not plug it up.