macro slider for panoramas?
I can't give you much advice on panoramas as I don't do many. However, I do use focusing rails quite a bit and I am aware that Manfrotto use 2 of their 454 micro positioning plates in one of their panorama heads. It can be seen on the link below which gives you an idea of how they are used.
I have one of these micro positioning plates. Although I've only used it for macro. The advantage of the Manfrotto 454 plate is that it is very low profile and locks down very solidly. In fact I often use it as an intermediary between the plate of the 410 geared head, which I am not so keen on, and another quick release system such as the RC2. However, whilst the 454 locks down very solidly it is not the smoothest macro rail as it uses a worm drive for adjustment, and not rack and pinion. For focus stacking I prefer a rack and pinion rail. This is because the adjustments are a lot smoother when it isn't clamped down. Screwing down the Manfrotto plate to lock it slightly changes the camera position. This is not a problem with wider framing where the fractional change in camera position makes no difference. However, with greater than life-size macro photograph, even just a tiny shift can alter the framing more than you would like.
Overall the Manfrotto plate works well for positioning and focus. It's a very low profile design and it's solid locking make it very stable. Some focusing rails lift up the camera quite a lot meaning there is a high centre of gravity and more flex, so they are less suited for being left permanently attached. However for focus stacking the rack and pinion rails are best, even the cheap ones from eBay. Whereas I often leave a Manfrotto plate permanently attached for most other tripod macro work. This allows me to move the camera backwards and forwards without having to move the tripod.
The Manfrotto 454 plate has a long slot that allows the camera to be positioned in different places along its length. At one end this slot comes quite close to the end, meaning the camera can be positioned close to the end of the plate. There is an adjustment knob that sticks out from the end of the plate by approx 2.5cm. In the normal position the tripod screw is around 6cm from the end of that knob. However, if you remove the rubber bung that stops the screw falling out you can place the camera a bit further forward, just under 1cm further forward. So I'd have thought that even with quite a short lens such as the Olympus 9-18mm you could position the camera so the end of the lens protuded just beyond the end of the rail (including the adjustment knob at the end).