Hong Kong's transportation is world class and there are going to be zero issues getting to the airport in the morning by either airport express (easier if you are staying near those locations) or a taxi. Hence there is no need to go to the hassle of changing hotels - especially since the airport hotels are, for the most part, not actually that convenient if you consider the need to wait for a shuttle bus and deal with construction (temporary). So yes, on timing, about an hour to get to the airport from most places is a reasonable plan via taxi - it would be even quicker on the airport express.

As for arriving early - well, that may be a good idea to enjoy the world class lounges (presuming you have access - ideally be a One World Emerald), but in reality as long as you hit check-in time (1 hour before departure for CX), you don't need to worry as security and immigration tend to be very quick.

For myself, as a frequent user of the airport, who also likes to have a meal before the flight, for a 10 am flight I would be aiming to leave my flat (near the JW Marriott) around 7am. I would get a taxi to the airport express (~10 minutes in light traffic) and then get the airport around 7.45-8.00am. About 5 minutes to check-in ( Cathay), and then within another 10 minutes time I'd be in the CX lounge. Boarding will start about 30 minutes before on a flight to TPE, so you'd be leaving the lounge (Gate dependent) about 45 minutes before the flight departure.

Finally, Hong Kong doesn't have rush hour at 7am (we prefer to get up late :P), it is busiest around 6pm, but even then you would be adding about 15-20 minutes of taxi queuing, at the worst case - its quick once you are on the highway.