Hi Mark,
I have the TS55 240v ( and a TS75 240v) and the TSC55. I tend to be using the TSC more and more often now, even when I'm in my workshop rather than out on a job.
It's just the convenience of no cord or extractor hose if I haven't got a lot of cuts to do.
If I'm breaking down sheets of material or I have a load of cuts to make in my workshop, then I set up one of my 240v saws with the extractor hose. The little dust bag on the cordless saw is okay if you only need to make a couple of quick cuts, but if you've got loads to do, the bag fills up really quickly and a fair amount of the dust doesn't get collected at all.....! The bag is convenient, just not particularly efficient....
Battery run time really depends on what you're cutting and how many cuts you're making, but as I use my saws in a professional capacity, I have spare 18v batteries on charge should the batteries in the saw be running low. I believe the new model cordless saw uses a thinner blade = easier cutting = less restriction = longer battery life, but I suppose that remains to be seen!
Personally, I wouldn't want to be without any my saws as they all have there place and strengths. Only you can decide which saw meets your needs best.
The "power" of the TS55 cordless saw is the same as the TS55 240v version during use and you wont notice any difference in this respect.
However,.....The cordless version is heavier with the 2 batteries fitted than the 240v version (5.3kg versus 4.5kg)
Hope this helps.
Tim.