Hey there,
So there is no perfect answer here. However, if you're plan is to go to self-directed investing, then it makes sense to move your WS Invest account to WS Trade. Now, I don't believe there is any rush to do it all at once. If this were me, I'd like move it over in chucks as I've identified equities or ETFs that I'd like to invest in. So as an example, say i have 10K in my WS Invest acccount and I seen an oppotunity in stock or ETF XYZ. I'd like my exposure to that particular asset to be around $2K. At that point in time, I'd move the 2K and buy it.
Since your WS Invest account is funded already, it is still compounding and making you money so there is no need to rush over all the holdings. Unless of course, you have a plan for that $$ already. Know what I'm saying?
In terms of your concerns re: International exposure, that is an easy fix. As you mentioned, you can simply by an International ETF like XAW. Alternatively, if you like the international holdings in your WS Invest account, you can either just leave that portion there or mirror that in your WS Trade account. Bottom line, there are several ways to address the international exposure aspect and I would not consider that a deciding factor in the move. I have three separate accounts, there is no 'need' to have but one.
It is worth noting that if one is looking to withdraw money in 3-5 years, this is still a shorter period timeline in the investment world. So it is important to take that into consideration when making your investment decisions. If it were me, the closer I got to withdrawal day, the more I'd consider moving my equity into fixed income as it really is the only way to guarantee capital preservation.
I am unclear about your last question - managing balance? Are you referring to how to balance your account after withdrawal? Without knowing your specific situation, if you are years out from retirement there is plenty of time to rebalance through new capital invested. When i first started out I cared less about a balanced portfolio and more about buying good stocks at good prices. As I get closer to retirement I start to pay more attention.
Mat