This is purely my 10p worth, but based on my own experiences with my 1976 Suzi triple 2-stroke, I've never had a single problem with modern petrol.

The tank was lined by the previous owner over 15 years ago, I've no idea what brand of liner was used. Over winter, the bike is often left for 6 - 8 weeks between rides, while waiting for a dry day. I never drain the floatbowls / tank, never use a fuel additive, nor get an exorcist in to pray over the bike :) and yet it always starts right up and runs clean (well, as clean as a 36-year old 2 stroke ever will ...)

For what it's worth, I fill up with Shell 9 times out of 10 (simply because it's the nearest to my house). Sometimes the V-Power, sometimes the regular stuff, it depends which pump is available.

Ethanol is endemic in most supermarket fuel. It is miscible with water and is hygroscopic so you run the risk of getting water in your fuel tank when the humidity is high or the temperature suddenly rises after a cold snap. In order to avoid this I use the higher octane stuff because it will have little or no bio ethanol in it in order to achieve the higher octane rating. This is especially important if you have a vehicle which will be left standing for any length of time.

This is the illusion under which I have lived in recent years and I may of course be wrong but I have had no fuel contamination or engine corrosion problems in the 8 vehicles which I run.

Like yourself my bike is left for probably half the year unused. I have had the same bike now for 13 years (CBF1000 ) so understand how it works. After several years of trying different solutions to the difficult to start and poor running in the spring I started using Shell V power and the problems have disappeared now for the last 5 or 6 years. I have been told from several sources that V Power has no ethanol added. Use it all the time now and the bike is the better for it.