There is (was, certainly, but I imagine still is) an airside immigration line for those connecting from international arrivals to domestic departures within KLIA1. I used it a couple of times connecting to Penang. I was equipped with an MH boarding card, but if you went for the MH service I'd hope you could get this through online check-in.

If you have to check-in (or if airside transfer is no longer an option), then after the regular immigration, with no wait for bags, it's easy enough to go up a level to the departure level and the MH desks, then security into the domestic departure area. With hours to spare this could be a stress free route, and there's an OK-but-nothing-special lounge on the other side if you have Oneworld status.

The Air Asia route could be handled in three hours, though I think I read the official (ultra-conservative) recommendation as four hours. Without major luggage it shouldn't be too difficult. Transport is by free bus or paid train. The train station is far easier to find than the bus stop: it's the regular KLIAExpress line - just be careful you get on the right train, or you get whisked off to the city.
KLIA2, the low-cost terminal, is a bit of a zoo-cum-mall but it works.

With the MH option you're likely to have excess time kicking your heels in a relatively comfortable environment, but you have allowed a wide contingency buffer for the late arrival of the EVA flight and avoided the clunky terminal transfer. You'd also gain a small handful of avios-whatever.

With Air Asia you potentially save time ..... and gain additional airport know-how first hand .