I'm a installer and do mostly residential work. I'm trying to decide on which tool(s) to buy for measuring air flow and such. I'm looking at the testo 435-4 or maybe just go with the testo H2 and the 405. I like how you can buy more "probes" that do more things for the 435 but it is more expensive. I would just need something to do velocity, CFM, ambient temps, WB, and all that stuff. Any opinions or thoughts?