I don't use nitrox, and have no intention of doing so. If, for some reason, I ever did, using the air-based calculations of a Veo 100 would give an extra margin of safety.
I have and sometimes use a Veo 100. It is a backup for my hand calculated modified tables. I use an excellent mini depth and pressure gauge, and a good watch. I'm very conservative. The Veo works fine as a backup, but I rely on my own brain. I dive for specific purposes, mainly sea life connected, and seldom dive deeper than about 25 meters. Scuba for me is a means to an end, not an end in itself. It lets me do more than breath hold diving permits, so I put up with the bulk of scuba equipment, reduced to a streamlined minimum.
The Veo is cheap, reliable, and does what I want it to. I've been diving since the 70s, so it's unlikely I'll suddenly decide to expand my horizons, technically.
Diving is a Zen experience. I enjoy spending an hour just examining the minute life thats developed on a mooring line, or the microcommunity under an overhang on the fore reef in 15 meters. Muddy back bays and mangrove areas near inlets can facinate for endless days of exploration.
Equipment is important, but its not what diving is about, at least not for me. My Mark 5 (1970) still words wonderfully well. I've updated the yoke to accomodate a 3500psi 45 cu ft steel tank for shorter dives, and a steel 80 for longer dives. I also use a Spare Air 1.7 as a bail out bottle. Considering I made the surface from 70 feet on one breath of air after I handed my entire rig to a homicidally frightened moron many years ago, I'm confident I can do it with three or four breaths. I never do decompression dives., of course. There is no reason for me to. I NEVER buddy dive, except with a few people I know extremely well. Otherwise, I keep my distance.
There is more variety in the Scuba world than many people might lead you to believe.
Get the Veo 100: less crap to drag around,and money to spend on other things.