Which is better for me ADSL1 or ADSL2

[#1]

By default my router connects on ADSL2, the downstream is usually in the region of 2500kbps with an upstream of 816kbps.
The theorectical maximum according to my router is 3962kbps. The downstream SNR is at 6.9 here on a none interleaved path.
If I manually force ADSL1, my downstream increases to around 2800kbps which a theoretical max of 3396kbps according to my router (and with SNR tweaking around 2900kbps stable which means I can get a .5mb ip profile increase) and the upstream is around 768kbps. The SNR is now at 10.8 and the path is intervleaved.
I live a fair distance from my exchange and I have heard that ADSL1 is infact better at holding a signal on a line with a long attn.
I know everything points to ADSL1 being better but is there a reason I should choose ADSL2?? will it ever achieve the theorectical speeds at which my router claims it can handle when the SNR ratio is only just at 6.8 (and below 6 i know it struggles), or should I leave ADSL1 on given I can get faster speeds, with a higher SNR?
The only downside to ADSL1 seems to be that it is using an interleaved path as opposed to ADSL2  which doesn't
Thanks for any input.

[#2]

Hi more information about your setup  would help. you mentioned you tweaked the snr does the line stay connected for days like this or does it become unstable.
where is the router connected master socket ? is there any extention wiring, sky box etc
router make model firmware if you know
ADSL filter type. dongle or faceplate?
line attenuation

finding out this info will help optimise  what you have.
ill check your post later
cheers defiant