Also budget for some good speaker mics. They make a big difference in emergencies. This is another difference between GOOD business-class radios, and the consumer-grade FRS radios or the Chinese-made amateur radios that some people repurpose toward business use - business-grade radios have the proper audio output to come across loud and clear on the speaker mic; FRS and amateur radios do NOT.
Speaker mics will never sound quite as good as the two-way radio in your hand but in an emergency, it is great to get it out of your hand and on your belt, with the speaker mic clipped to a collar.
Because the DTR and DLR radios are high-quality, military-grade radios, they use the Motorola two-pin headset socket, not the consumer-grade Talkabout single pin. Match them with a really good quality speaker mic - which is really not that expensive these days in comparison to the radios - and you have a good communication system.
I would urge you again to borrow or rent a couple before you make a final decision, and see if you need a repeater or not. It will then be up to you as to whether you want to invest in a business licence with a dedicated frequency, business-class radios and a repeater system, or just go with the licence-free DTR radios.
Let us know what the boss says. Personally, I am a huge fan of the DTR radios and have used them for years. The forum hosts at Buy Two Way Radios probably know more about radios in general, and the DTR radios in particular, than most dealers, and can help guide you.
Also, before you decide, do some research on the DLR radios. They have similar performance as the DTRs, and are slightly cheaper. They are smaller and lighter, but you lose a couple of features, such as the ability to call up an individual radio, part of a group or an entire group. They are durable, but not quite as water resistant as the DTR.