I used the Pro Chrono for a while and was very happy with it, but also have the new Caldwell.
I had some concerns over the 'cheapness' of the Caldwell unit (as in, will it last, or become another disposable item?), but so far I've been happy with it, other than the tripod with the 'deluxe' kit is meant for midgets and needs to be replaced - too short to shoot standing pistol, and pretty flimsy overall, but good enough for rifle.
The main reason for buying the Caldwell is the price of the remote kits for the Pro Chrono is the same or higher than the price of the Caldwell chrono, which uses a smart phone or tablet as the primary display and input mechanism. When shooting at public ranges that are
not busy or on a private range, the Pro Chrono is great, but when working up/testing a dozen or more loads at a busy range, the remote is almost required, or a whole lot of wait/down time. The last outing with the Pro Chrono had me using a broomstick to try to press the 'string change' button w/out crossing the firing line...
The Caldwell isn't perfect - I usually need to plug in the cable, remove, plug back in to phone and/or chrono at least once before it gets a 'solid' connection..having said that, once it gets a connection between phone and chrono, it's yet to lose it, including through a full afternoon with hundreds of rounds over the unit. With that in mind, I cable it, throw it on the tripod (one I had, not their supplied POS), start the app and turn the chrono on, and check to ensure it's got a connection established
before I move the chrono down-range.
I would wager the Caldwell software is done in a 'low cost geography' as the first version was very much alpha-feeling, but they have made numerous app updates over time, and it's now pretty decent, allowing you to 'stage' or pre-enter the strings you plan on testing before being on site at the range, and a few other enhancements. You have the option to SMS/text or email your load results from your phone, although I'm still waiting for automatic Dropbox sync/export.
Back to back shooting 9mm Minor-ish loads (115-140 Power Factor), including one of my 'standard' 130PF loads, the Caldwell and Pro Chrono have been very close to each other, within 10FPS or so for 10 shot string averages, while many have favorably compared the Pro Chrono to the various $$$ chronos used at matches, so more or less I'm going with - it's accurate enough for most purposes.
Were I going to use it only at a private range, I'd go with the Pro Chrono, as they stand behind their product, and I've heard of people shooting theirs to still get it 'fixed'/replaced for a good price, but if your typical use is at a public or busy range, you'll want to consider the options and total cost for a remote.
YMMV as always - ask me in another couple of years, as the question remains - will both last for at least 10 years?
