After losing the bulk of my discus when lightening struck outside my house, I don't trust any heaters either, including those with external controllers, except analog Via Aqua's but they are no longer made.
I would like something with a high/low temp alarm, and I do kind of like the wifi idea so you have a backup warning if you're not home or paying attention.
Another option is to use an ST-1000 controller but you'd have to construct a housing to make it visually appealing, unless you don't care what it looks like. I have several but I haven't used any yet.
If you have that much trust in Ranco's, I'd stick with that!