Hello Andrew,
L does stand for long table. I think about 6" longer.
This was introduced about four years ago as a way to compete vs the other competitor – such as Optimum offerings in this size. You guys are just seeing it now.
At that time, there was a big debate between myself, the chief engineer at SIEG and the management. Many of the importers wanted an even longer table than the L you see. The chief engineer and I insisted on keeping to the standard, but if the other importers and management wanted a longer table, it needed to be in proportion with the column, in terms of 'look'. The chief engineer and I did not want it to look like an 'un-balanced' machine. So, 6" longer was 'settled' on as a compromise. The label 'L' was chosen by me.
. This was to fall in line with the SX1L and the SX2LP (P was just to signify brushless motor fixed column – no other reason)
The key reason why the chief engineer and I didn't want to increase the table length, even by 6" was that we were not a 100% happy about how well the table with longer length could be supported on the saddle, without bowing on each end. To this day, we question the logic of small mills with longer tables, even if we are proved wrong. Before anyone says anything, even the respected Bridgeport/clones can suffer from this, depending on very factors. I have this on authority from respected users of Bridgports.
With the 6" longer length, in my opinion you will be at the maximum limits of suitability. We ARC sold the L version for just under two years. Sales were poor due to many of our customers in U.K. having limited space in their workshops. If you have more space, then you may want to consider the 'L' version.
The key difference between the SX3/SX3L and the alternative competitor machines in your market is that the SX3/SX3L has a brushless motor with HiTorque programming on the control board. The competitors have brushed motors, and some of the competitors in your market are incorrectly specifying 'input' wattage in their marketing to suggest that they are offering a more powerful machine in comparison to the SX3L. Other then this key difference, machine builds for competitor models in this size range are broadly similar. The final choice is really yours.
Ketan at ARC