Well, as for being a “first timer”, unless there’s a totally new system out there the way most of us learn is by being a shingle monkey & then working our way up as we pick up new skills or abilities.
Note: general handyman types do not apply here.
As for the metal, I say “no” - aluminum would be an insane price point. Not in my opinion, anyhow. One of the benefits of a metal roof is a % reduction on insurance both in your wind & hailstorm endorsement portion of your premium as well as in your deductible should you ever have to file. To get this same deduction out of aluminum, you’d have to get a thickness that would be price prohibitive IMO. Galvanized is the best option; has more of a “traditional” Texas look, however your home’s architectural style may not lend itself to all types of “straight line” metal roofing.
The coated surface is there just so the roof doesn’t look metal. There are also cedar shake look alikes as well as a lot of other types of metal. Decra has one as well, IIRC.
Keep in mind that here in Texas, a metal roof is going to cost you about 2-1/2 to 3=1/2 times the price of a typical shingle roof.
If you currently have a tile roof & want to switch to something else, there are co’s who will purchase the tiles right off your roof, thereby lessening your financial outlay.
I’m not familiar with Kassel & Irons or Classic Metal Roofing Systems; I’ll have to look them up. If you can, post some photos of the house & if you’d like, we can discuss metal options (one of my metal foremen lives in San Marcos, the other in South Austin).
Ranch Hand Roofing