Whether the OP appreciates my comments is up to him, but I couldn't give a tinkers either way. 
To set the picture I have a Harrison M300. I bought it about 15 years ago, from a dealer. It is imperial, 40" between centres and has the removable gap piece. It's all very well people lauding excellent, but esoteric, lathes; the chances of finding one are worse than the lottery. At least the M300 sold well and there are plenty about; whether they're worth buying is another matter. If one excludes a lathe I bought, and later sold, while I was at school the M300 was my first lathe.
Before one starts to look there are a few decisions to be made:
1. Imperial or metric, probably depends on what type of threads one is most likely to be screwcutting
2. Distance between centres, 25" or 40"
3. Straight bed or gap piece
When I looked at my lathe before buying I insisted on seeing it run, we probably didn't run at the top speed, but enough to be happy with the headstock gears. Likewise we didn't try all the feeds, but enough to be sure basic feeds and screwcutting was working. I actually looked at two M300s at the dealer, one 25" and the 40". I really wanted the 40", but the 25" was superficially better equipped with QCTP front and rear, and cleaner. I didn't buy it as there were clear ridges on the bed ways. In retrospect that was a good decision, I don't use QCTPs so I'm lucky I wasn't seduced by them.
I didn't do much in the way of testing, just a twiddle of all the handles to make sure everything was smooth with full movement. I also moved the saddle the full length of the bed, of course it got tighter near the tailstock but still perfectly usable. One gets a "feel" for the lathe, it was obviously used, but the paint wasn't too bad, and was basically clean. I'd never buy a machine tool that has recently been painted, unless there was documentary evidence of a proper rebuild. Too much emphasis is placed on backlash. Even if the bed is worn that may not be serious if you turn larger work. Suppose you're turning a 1" diameter, how much will the diameter change for a 10 thou drop in the tool? The bed on my lathe seems ok, but the cross slide gib is at the limit of it's adjustment and the backlash is around 15-20 thou. But so what? It doesn't affect the ability to turn out accurate work. I can work to a thou or better if needed, the limitation is the operator not the lathe. 
Since I bought the M300 and a Bridgeport the dealer threw in free delivery and some other accessories. Having looked at both machines I went and had a pub lunch with my mum, before going back to complete the purchase. I normally like to have a breather on the bigger purchases before deciding.
The M300 has all the usual accessories available for most lathes, whatever their source. Prices seem to have got a bit silly recently. To some extent the deal maker or breaker is the tooling. It' probably easiest if I list the accessories and my take on them:
3-jaw SC chuck – came with the lathe but it's fudged (quality make but very worn) so I rarely use it
4-jaw independent – came with the lathe, in good condition and I use it a lot
Burnerd collet chuck – thrown in as deal sweetener, excellent move, as I use it a lot, the collets go to 1½" so replace the 3-jaw for much work
4-way toolpost – came with the lathe
small (12" ) faceplate – bought on Ebay at a later date, don't use it much as it's a bit small (!)
large (18" ) faceplate – bought later from a different dealer, gets used quite a lot when I need to do faceplate work
Drill chucks – bought later on Ebay
Taper turning – I don't have this accessory and don't really need it – see later
Multi bed stop – I don't have one, but would really like one, but they seem quite rare on their own
Rear toolpost – I don't have one, I'd buy one if the price was right, but I don't have a pressing need for it
Fixed steady – came with the lathe and I've used it quite a lot
Travelling steady – bought later from a dealer at an ME exhibition, never used it so far
Extra change gear for DP/module – bought later on Ebay but not used so far
Catch plate – bought later from another dealer and used once
Centres – bought new as needed
Flood coolant – came with the lathe
Since the M300 is an industrial lathe there are some accessories that are not generally available for ME style lathes:
Capstan unit – bought later on Ebay, I have used it but it is now somewhat superceded by my repetition lathe
Ainjest high speed threading unit – bought later from a dealer, very useful for all imperial threading, makes it a doddle to screwcut into a blind hole at several hundred rpm
Hydraulic copy unit – bought later on Ebay, when you need fancy shapes it doesn't half make life easier, and it's why I'm not bothered about a taper turning unit
More to follow!
Edited By Andrew Johnston on 09/11/2017 23:00:09