I will be traveling from the Philippines to Germany on Emirates, with an 8 hour layover in Dubai (01:00AM - 09:00AM). Since the in Terminal Hotel is very pricey I was thinking about booking a room in a hotel just outside the Terminal. I was reading that the waiting times for immigration can be very long in Dubai, so I have my doubts if it makes sense to book a Hotel to catch some hours of sleep. How long do you think will it take to get from the plane through customs and out of the Terminal? My bags will be checked through to Hamburg, so hand luggage only.
As an alternative to off-site hotels, you might consider accessing an airside lounge that is open overnight, either by payment or by membership or status. See here: http://www.sleepinginairports.net/mideast/dubai.htm#lounge
According to my experience, time to get out of DXB airport can vary from 20 minutes if everything goes well to more than 1 hour. But from what I have seen, it usually works well. I am not sure where you have heard that it could take time but this is far from being the worse airport in the world from that standpoint. I have seen places where you could wait for 2-3 hours without any exceptional circumstances. This isn't the case in DXB. I was able to get out of the airport pretty quickly most of the time.
Then, with regards to the hotel, you will find a lot of hotels in DXB which are cheaper than the airport hotel. And you won't need 2 hours to get there, only few minutes. So if you have 8 hours of layover, I believe you could sleep for around 5h30 minutes.
I work in the airport, it is not crowded at 1am at the immigration counters, besides if you are european, you can use the smart gates, which should't take you more than a minute or two to go through that.
it is worth to mention that Emirates airlines passengers, with at least 8hrs of transit time can get free hotel voucher that includes transport, meals, visa if required, check with the call center or online if you are illegible.