If you are truly concerned about break in prevention, all doors (with the exception of multi-point lock steel units) will have weak points.

If you are really concerned, a good security storm door an NRA sticker will do wonders.

ThermaTru doesn't make their own lock last I checked.

The Emtek lock is a nice system.

Thanks Windowsonwashington. I didn't think storm doors were security doors. The ones I've seen are glass. What type do you refer to?

Regarding the Therma Tru multilock system, I just wanted to say for anyone else who may refer to this thread, that in researching the multilock a bit more, we've learned that the multilock cylinder can only be replaced with a "Schlage" brand cylinder. This brand is sold at Lowwes. We also learned that dummy keys or rekey kits are readily available.

Storm door are not necessarily security doors but they can be.

Depends on the manufacturer.

dilly, this link below is an example of what WoW was referring to. May have glass, but with welded steel bars and a doubled keyed deadbolt this will not be the easiest point of entry for a break in.
Regarding the multi-point lock, it will offer some improved security, but the jamb is typically the weak point in a door assembly. Some products have heavy gauge steel reinforcement in the jambs.
Other doors that may be in the same price range: Provia, HMI, Polaris, and Homeguard.

Here is a link that might be useful: security doors

Thanks for your help. I priced a Provia door with transom today and it was 4x the cost of Therma Tru and double the cost of Pella, but that cost included installation. It is very difficult to tell the quality differences from showroom displays.

Provia is certainly a premium door but you need to compared installed prices to get the fairest comparison.