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Quick verdict
Choose the SlimBlade Pro if you want finger-operated control, an ambidextrous layout and ball-twist scrolling. Choose the MX Ergo S if you prefer a right-handed sculpted shape and thumb control. Neither is a universal comfort upgrade; the control method is the decision to settle before comparing extra buttons.
Research-based buying guide, checked October 18, 2026. We have not tested these products hands-on. Manufacturer specifications and attributed outside findings are distinguished from our buying judgments.
Who should buy or skip
Buy if: you want to move the pointer without repeatedly sliding a mouse across the desk and will allow time to learn a different technique.
Skip if: you already work comfortably with a mouse, cannot try an unfamiliar shape or expect a trackball to treat pain.
Compare the choices
| Choice | Choose it for | Main tradeoff |
|---|---|---|
| SlimBlade Pro | Finger control, either-hand use and twist scrolling | Its scrolling gesture takes practice |
| MX Ergo S | Right-handed thumb control and an adjustable tilted position | Unsuitable for left-hand use; thumb work remains |
| Keep a regular mouse | Familiar control that already works | Still requires room to move it |
Your hand chooses the more useful feature set
Kensington places the ball under the fingers; Logitech places it under the thumb. That changes which movements you repeat and where the clicking fingers rest. A trackball may save pointer-travel space while still needing room for a relaxed hand and forearm.
The MX Ergo S is shaped for right-hand use, and Logitech describes its fit as medium to large hands. The SlimBlade Pro’s ambidextrous arrangement is more adaptable for left-hand use or switching hands. Do not use a feature score to override a poor physical fit.
Scrolling is not a minor detail
SlimBlade Pro scrolling comes from twisting its large ball. MX Ergo S uses a separate scroll wheel alongside thumb-operated tracking. If you spend the day in long documents or spreadsheets, imagine doing that action repeatedly rather than focusing only on pointer precision.
RTINGS’ original SlimBlade Pro assessment is useful for understanding its productivity focus and unusual control layout. It is outside testing, not ours, and it cannot establish which movement will feel natural to you. Try both scrolling and drag-and-drop during a return window.
Compare connections and charging carefully
Kensington specifies Bluetooth, 2.4 GHz wireless and wired operation for the SlimBlade Pro. Logitech lists quick USB-C charging for the MX Ergo S; a charging socket should not be assumed to provide the same wired data mode.
Check whether the exact package includes the wireless receiver and charging cable you need. Logitech distinguishes the MX Ergo S from an older MX Ergo, and its Plus version adds an extra wedge. Do not pay for a listing that quietly substitutes an older model or a different bundle.
A good trial includes your normal work
Spend time selecting small spreadsheet cells, editing text, dragging files and moving between monitors. Start with moderate pointer settings and change one option at a time. An unfamiliar motion can feel awkward initially, but persistent discomfort is not a reason to force adaptation.
Plan for basic cleaning according to the manufacturer: debris at the ball supports can change the feel. We have not measured these models’ long-term wear or noise. Advertised ergonomic benefits and quiet-click language are not a promise of comfort or silence in your room.
Buying in the United States or Canada
Look for SlimBlade Pro rather than the original wired SlimBlade, and MX Ergo S rather than the earlier MX Ergo. Check the precise regional SKU, receiver, charging cable and whether a Logitech extra wedge is included. Prefer local returns for a product whose usefulness depends so heavily on hand fit.
The buttons open the named country’s Amazon search results. Match the exact model, size and included parts before ordering. Compare delivered cost, seller and return terms; no fixed price, availability or warranty eligibility is promised.
Questions before ordering
Can a left-handed person use MX Ergo S?
Its shape and thumb-ball position are designed for the right hand. The ambidextrous SlimBlade Pro is the relevant option in this pair for left-hand control.
Does a trackball need no desk space?
The device stays in place, but its base and your supported hand still need room. Measure the complete working position.
Final buying decision
The SlimBlade Pro is our choice for finger control and either-hand flexibility. The MX Ergo S is the better match for someone who already likes right-handed thumb trackballs and wants its tilted support. If you have never used either style, a returnable trial matters more than a small price difference.