In the end I did decide to go with the Celestron Nexstar 127 SLT, the decision between that and the Sky-Watcher being largely based on comments about the quick and easy set up/alignment of the Nexstar mount.
So far I'm extremely happy with my decision. This 5" goto Mak is exactly what I was after, compact and lightweight enough to be easy to store, move and set up but with enough aperture and focal length for good lunar, planetary and solar views and quick enough to set up that it's still worthwhile getting out even if I can only spare an hour or so. The included eyepieces aren't fantastic (noticeable chromatic aberration and image softness away from the middle of the field) but as far as I can tell the optics of the OTA itself are good, and collimation was spot on out of the box. For the price it really is impressive overall.
It is true that the included tripod is very wobbly but I've found that was significantly improved by using it with the legs at the minimum extension required for levelling rather than the 6-8" mentioned in the manual. With the scope that low to the ground the straight through red dot finder can be a bit awkward to use but at least the mount is then tolerably stable.
Unfortunately I was hit by the Celestron firmware corruption bug 6 days after buying the telescope, when I turned the telescope on the handset displayed "Bootloader invalid package 0080” and refused to work. According to the
Celestron webpage about this problem the official solution to "my new Celestron telescope is broken" is "buy these additional Celestron accessories so that you can fix it yourself", an attitude I wasn't impressed by. Fortunately when I contacted Andrews they immediately offered to exchange the handset for a new one and updated the firmware while they were at it, very satisfied with the customer service there. To Celestron's credit when I did complain to their technical/customer support about their policy they did offer to send me the proprietary Nexstar RS-232 cable needed to re-flash the handset firmware but given that this is a known problem I still think they should be including it in the box with the telescopes.
Anyway, wobbly mount and firmware glitch aside I've been really enjoying the views of the Sun, Moon and Jupiter I've been able to get. With a cheap
Lorng Perng digiscoping adaptor and my Sony RX100 I've even been able to get some half decent images. Below is my best effort to date, an image of Europa, Jupiter and Io obtained from processing a 30 second video clip in Registax 6.