The Pace S tops our $1,000 tier at $1,000 even; the Proton sits a tier up at $1,695. That makes this the most natural cross-shop in our tennis evidence - and the roughly-$700 question has a more interesting answer than more money, more machine.
Both are app-first machines with genuinely deep evidence pools - 85 sources combined. Every claim below traces to a dimension on the product pages.
The short answer
The Pace S is the stronger all-rounder: flawless real-performance evidence, AI placement that reacts to where you stand, and an 8-hour battery record without a single complaint. The Proton buys you one thing decisively - portability in a class of its own, at a hopper-of-balls weight the Pace S's 38 pounds cannot match - and asks you to accept the weaker build record of the two.
Portability
This is the Proton's dimension, and it is not close: nine of nine sources positive, with reviewers repeatedly comparing the carry to a hopper of balls - fold it, pick it up, no wheels needed.
The Pace S is no brick - at about 38 pounds owners report any family member can carry it - but it is a machine you load into a car, not one you sling over a shoulder.
Smart training
Neither app has a negative report anywhere in the evidence. The difference is what sits behind them: the Pace S's AI mode tracks where you are on court and adjusts placement in response - the closest thing to a moving opponent at this price - and its drill community lets you copy other players' routines.
The Proton counters with clean fundamentals: fully programmable feeds, quick drill creation, shot-count tracking, and a calibrate-and-go first shot. An excellent app with less ambition behind it.
Power and performance
The Proton has the raw numbers: 70 mph top speed and up to 3,000 RPM of spin, with serve-speed practice specifically called out. Its caveat is aim - sight-to-sight drift appears in its performance evidence.
The Pace S's performance pool is the deepest either machine has - sixteen qualified sources with every scored one positive. What it gives up in headline speed it returns in consistency of the record.
Reliability and upkeep
Neither build record is spotless, but they differ in kind. The Pace S's build pool splits roughly in half, with the plastic casing drawing most of the negative reports on a machine many owners still call solid and sturdy.
The Proton's build reports are mechanical - double-firing, balls sticking in the carousel, a feeder tray that wobbles after cleaning, and drift after a full basket - one positive source against four negative. Battery depth differs the same way: the Pace S has nine complaint-free sources behind its 8-hour record, while the Proton's battery pool is a single source plus Ryobi-pack compatibility.
Verdict
Spend the extra roughly $700 only if carry weight decides whether you actually practice - for walk-on courts and daily hauling, the Proton's portability evidence is unmatched. For everyone else, the Pace S keeps the deeper evidence in performance, battery, and build, and its AI training is the feature the Proton cannot answer.
Where these picks rank
Frequently asked questions
Is the Proton worth about $700 more than the Pace S?
Only if portability is the deciding constraint. The Proton's hopper-of-balls carry is the single strongest dimension either machine has, but the Pace S matches or beats it everywhere else in the evidence - performance depth, battery record, and build. The extra money buys carry weight, not a better all-round machine.
Which app is better?
Both are almost unanimously liked, so the tie-break is ambition: the Pace S app adds AI placement that responds to your court position and a community for sharing drills, while the Proton app keeps to fully programmable feeds and shot tracking done very well. Feature-wise the Pace S asks for more and delivers it.
Which is more reliable?
The Pace S has the better record. Its build complaints cluster on the plastic casing of a machine many owners still call solid; the Proton's are mechanical - double-firing, a wobbling feeder tray after cleaning, and drift after a full basket - at one positive source to four negative. Neither is club-metal, but the natures of the complaints differ.