and is there that much difference between them all?

Weight and price, lighter equals dearer

for dh you have saint and zee

ime there isnt much performance difference betwwen deore and xt, just weight saving really

(im too poor to run xtr)

LX is more of a hybrid groupset now and not mtb. SLX is its supposed replacement.

I found XT shifters feel a lot better than deore shifters but the same is not true with derailleurs.

Apart from that it’s mostly a weight difference

is lx still robust enough for mtb?

Shimano’s MTB groupsets are:

XTR/XT/SLX/Deore/Alivio/Acera

LX is now a trekking groupset.

Even the lower end stuff is pretty decent kit, but I would say that the 2013 SLX stuff is in a pretty good ‘sweetspot’ of price and function. Marginally heavier than XT, but nearly the same performance.

cheers what is the difference with the numbers 770 751 and so on

Higher the number, newer the groupset, i.e. M751 = 1998, M785 = 2012

4 digit number are for road groupsets, M=3 digit = MTB, MX+2 digit = BMX, T+3 digit = Trekking; also expect some crossover with parts

For MTB, within that, first number indicates level, M6** = SLX/Zee M7** = XT, M9** = XTR etc

That’s it in really simple terms, google Shimano date codes, and there is plenty of info out there, especially for the older parts; just because a part is listed as a model year, it will probably have been available earlier than that, 2013 parts are in the shops now for some groupsets.