Ops found it after all.
Hi woodbloke. It's all a bit relative really. The mitre fence is very good but possibly not as accurate as some of the after market mitre fences available especially from the States or Canada. The main problems with the Jet are that there's no left hand mitre slot so an after market upgrade wouldn't be possible unless you are prepared to work left handed. The right hand slot is quite far from the blade when compared to other saws. Capacities are small when compared to the SIP or a clone of it.
Everything else is A+. Top is precission ground and flat as a pancake. The SIP's is not. My mate has the Fox model and if you put a straight edge front to back the whole top dips, and I kid you not, by 2mm in the middle. The fence is just as good as the SIP's but doesn't have a fine adjustment knob but does have a split fence on the UK model unlike the SIP. The mitre slot is acuratley milled in and you'll find very little play if you do try a small mitre gauge in it. This has been a problem area on all the SIP derivatives often commented on on this forum. I know some owners have sent machines back because of it. The rise and fall is first class and way way way better than the SIP. There's no play at all and it's silky smooth even after a year of heavy use. The SIP models suffer 'backlash' so after say raising the blade by turning the hand wheel clockwise there's 10-20 degrees of play when you turn the wheel anti clockwise before the blade starts to lower. This is due to cheap worm gear which also gets clogged with dust and becomes increasingly stiffer with age unless you regularly clean and oil the worm drives. The jet has a belt drive system with tensioners to take up any slack. The only down side with this is that there is a potential for a belt to snap and you would lose your rise and fall. There is a significant amount of disassembly to renew the belt which thankfully I have not yet had to do but is a complaint of Supersaw owners over the pond. The crown guard extraction on the Jet is also better. The Jet's sliding table only has a capacity of 2 feet in front of the blade and the ali fence is only about 2 feet long, both significantly smaller than the SIP's. That said the sliding action 10 times better and the sliding top is all cast iron where as the SIP's is pressed steel and is prone to rusting. The blade insert plate on the SIP is only around 3mm deep. This means making a zero clearance insert is a problem. You can make the insert out of 3mm hardwood but it will have warped in a week or you can make it out of thicker material and route the edge down to 3mm. That's still not especially strong. The best option is to make one out of perspex but that's costly. The Jet's insert is a meaty 7mm or so deep so theres no problem here. Two more considerations are that the SIP has, or at least did have a 16mm arbour which limits you choice of blades. 30mm is the most common and that's what the Jet has. However the Axminster and Fox models have a 30mm arbour.
Finally there's the price. The Jet is £400 more than the Axminster model. So is it worth the extra? It's a close call. People bang on about the SIP's capacities but many just make boxes or other small stuff. I tend to make furniture and larger pieces and haven't found the lack of capacity limiting although a longer sliding table fence would be nice. I'm lucky in that I have a mitre saw station so this is not an issue but you could really do with a longer fence if you didn't have a chop saw. I bought this saw as an end of line from Axminster. It was on ebay and didn't sell so I rang them and offered £500 inc Vat which they excepted so the machine arrived new in the box but with no warranty. For like for like money there's no contest, go with the Jet but at £400 more????? Put it this way...when I rang them and offered £500 the plan if they said no was to order the Axminster/SIP clone instead on the same phone call. Best to try each yourself!